We report the identification and characterization of myr 4 (myosin from rat), the first mammalian myosin I that is not closely related to brush border myosin I. Myr 4 contains a myosin head (motor) domain, a regulatory domain with light chain binding sites and a tail domain. Sequence analysis of myosin I head (motor) domains suggested that myr 4 defines a novel subclass of myosin Is. This subclass is clearly different from the vertebrate brush border myosin I subclass (which includes myr 1) and the myosin I subclass(es) identified from Acanthamoeba castellanii and Dictyostelium discoideum. In accordance with this notion, a detailed sequence analysis of all myosin I tail domains revealed that the myr 4 tail is unique, except for a newly identified myosin I tail homology motif detected in all myosin I tail sequences. The Ca(2+)-binding protein calmodulin was demonstrated to be associated with myr 4. Calmodulin binding activity of myr 4 was mapped by gel overlay assays to the two consecutive light ...
Myosins are actin-based motor proteins involved in many cellular movements. It is interesting to study the evolutionary patterns and the functional attributes of various types of myosins. Computational search algorithms were performed to identify putative myosin members by phylogenetic analysis, sequence motifs, and coexisting domains. This study is aimed at understanding the distribution and the likely biological functions of myosins encoded in various taxa and available eukaryotic genomes. We report here a phylogenetic analysis of around 4,064 myosin motor domains, built entirely from complete or near-complete myosin repertoires incorporating many unclassified, uncharacterized sequences and new myosin classes, with emphasis on myosins from Fungi, Haptophyta, and other Stramenopiles, Alveolates, and Rhizaria (SAR). The identification of large classes of myosins in Oomycetes, Cellular slime molds, Choanoflagellates, Pelagophytes, Eustigmatophyceae, Fonticula, Eucoccidiorida, and Apicomplexans ...
Conventional myosin (myosin II) is a major component of the cytoskeleton in a wide variety of eukaryotic cells, ranging from lower amoebae to mammalian fibroblasts and neutrophils. Gene targeting technologies available in the Dictyostelium discoideum system have provided the first genetic proof that this molecular motor protein is essential for normal cytokinesis, capping of cell surface receptors, normal chemotactic cell locomotion and morphogenetic shape changes during development. Although the roles of myosin in a variety of cell functions are becoming clear, the mechanisms that regulate myosin assembly into functional bipolar filaments within cells are poorly understood. Dictyostelium is currently the only system where mutant forms of myosin can be engineered in vitro, then expressed in their native context in cells that are devoid of the wild-type isoform. We have utilized this technology in combination with nested truncation and deletion analysis to map domains of the myosin tail ...
Using optical trapping and fluorescence imaging techniques, we measured the step size and stiffness of single skeletal myosins interacting with actin filaments and arranged on myosin-rod cofilaments that approximate myosin mechanics during muscle contraction. Stiffness is dramatically lower for negatively compared to positively strained myosins, consistent with buckling of myosins subfragment 2 rod domain. Low stiffness minimizes drag of negatively strained myosins during contraction at loaded conditions. Myosins elastic portion is stretched during active force generation, reducing apparent step size with increasing load, even though the working stroke is approximately constant at about 8 nanometers. Taking account of the nonlinear nature of myosin elasticity is essential to relate myosins internal structural changes to physiological force generation and filament sliding.. ...
TY - JOUR. T1 - High-performance ion-exchange chromatography of myosin using a DEAE-5PW column. AU - Lema, Mark J.. AU - Pluskal, Malcolm G.. AU - Allen, Paul D.. PY - 1989. Y1 - 1989. N2 - High-performance ion-exchange chromatography of myosin using a DEAE-5PW packing was used to purify myosin from skeletal, cardiac and smooth muscle. This method produces high-speed resolution (30-min analysis) of myosin from contaminating myofibrillar proteins. The column has a high capacity for binding myosin (up to 1 g) and can be used for small-scale preparation of highly purified myosin. Gel analysis in the presence of sodium dodecyl sulfate showed recovery of myosin with very little contamination of other myofibrillar proteins. Myosin was also recovered from small biopsy samples (0.1 g) by a direct extraction technique with recovery of biological ATPase activity.. AB - High-performance ion-exchange chromatography of myosin using a DEAE-5PW packing was used to purify myosin from skeletal, cardiac and ...
Muscle, motor unit and muscle fibre type-specific differences in force-generating capacity have been investigated for many years, but there is still no consensus regarding specific differences between slow- and fast-twitch muscles, motor units or muscle fibres. This is probably related to a number of different confounding factors disguising the function of the molecular motor protein myosin. We have therefore studied the force-generating capacity of specific myosin isoforms or combination of isoforms extracted from short single human muscle fibre segments in a modified single fibre myosin in vitro motility assay, in which an internal load (actin-binding protein) was added in different concentrations to evaluate the force-generating capacity. The force indices were the x-axis intercept and the slope of the relationship between the fraction of moving filaments and the α-actinin concentration. The force-generating capacity of the β/slow myosin isoform (type I) was weaker (P , 0.05) than the fast ...
Caldesmon interaction with smooth muscle myosin and its ability to cross-link actin filaments to myosin were investigated by the use of several bacterially expressed myosin-binding fragments of caldesmon. We have confirmed the presence of two functionally different myosin-binding sites located in domains 1 and 3/4a of caldesmon. The binding of the C-terminal site is highly sensitive to ionic strength and hardly participates in acto-myosin cross-linking, while the N-terminal binding site is relatively independent of ionic strength and apparently contains two separate myosin contact regions within residues 1-28 and 29-128 of chicken gizzard caldesmon. Both these N-terminal sub-sites are involved in the interaction with myosin and are predominantly responsible for the caldesmon-mediated high-affinity cross-linking of actin and myosin filaments, without affecting the affinity of direct acto-myosin interaction. Binding of caldesmon and its fragments to myosin or rod filaments revealed affinity in the ...
Mts1 protein (S100A4 according to a new classification) has been implicated in the formation of the metastatic phenotype via regulation of cell motility and invasiveness. Previously we have demonstrated that Mts1 protein interacted with the heavy chain of nonmuscle myosin in a calcium- dependent manner. To elucidate the role of the Mts1-myosin interaction, we mapped the Mts1-binding region on the myosin heavy chain molecule. We prepared proteolytically digested platelet myosin and a series of overlapped myosin heavy chain protein fragments and used them in a blot overlay with Mts1 protein. Here we report that the Mts1-binding site is located within a 29-amino acid region, at the C-terminal end of the myosin heavy chain (between 1909-1937 amino acids). Two-dimensional phosphopeptide analysis showed that Mts1 protein inhibits protein kinase C phosphorylation of the platelet myosin heavy chain at Ser-1917. We hypothesize that Mts1 protein regulates cytoskeletal dynamics of the metastatic cells ...
Contractile agonists can mobilize Ca2+ from both intracellular and extracellular stores in smooth muscle. This study addresses the role of Ca2+ mobilization as it relates to the complex manner by which Ca2+ regulates the contractile system in smooth muscle. In swine carotid media, both histamine and phenylephrine produced initial rapid increases in myosin phosphorylation and stress. Stress was sustained for the duration of the stimulus while myosin phosphorylation slowly declined to steady-state levels. Removal of extracellular Ca2+ or elimination of cellular Ca2+ influx did not dramatically reduce the initial rapid increase in myosin phosphorylation produced by either agonist but reduced steady-state levels of myosin phosphorylation to basal values. Initial rapid increases in stress were seen, but stress was not maintained. Following depletion of Ca2+ from sarcoplasmic reticulum, muscle activation by Ca2+ influx in the presence of phenylephrine occurred without an initial transient in myosin ...
TY - JOUR. T1 - Characterization of myosin V binding to brain vesicles. AU - Miller, Kyle E.. AU - Sheetz, Michael. PY - 2000/1/28. Y1 - 2000/1/28. N2 - Myosin II and V are important for the generation and segregation of subcellular compartments. We observed that vesicular myosin II and V were associated with the protein scaffolding of a common subset of vesicles by density sedimentation, electron microscopy, and immunofluorescence. Solubilization of either myosin II or V was caused by polyphosphates with the following efficacy at 10 mM: for myosin II ATP-Mg2+ = ATP = AMP-PNP (5- adenylyl imidodiphosphate) , pyrophosphate = tripolyphosphate ,, tetrapolyphosphate = ADP , cAMP = Mg2+; and for myosin V pyrophosphate = tripolyphosphate , ATP-Mg2+ = ATP = AMP-PNP ,, ADP = tetrapolyphosphate , cAMP = Mg2+. Consequently, we suggest solubilization was not an effect of phosphorylation, hydrolysis, or disassociation of myosin from actin filaments. Scatchard analysis of myosin V binding to stripped dense ...
1. Combined histochemical and biochemical single-fibre analyses [Staron & Pette (1987) Biochem. J. 243, 687-693], were used to investigate the rabbit tibialis-anterior fibre population. 2. This muscle is composed of four histochemically defined fibre types (I, IIC, IIA and IIB). 3. Type I fibres contain slow myosin light chains LC1s and LC2 and the slow myosin heavy chain HCI, and types IIA and IIB contain the fast myosin light chains LC1f, LC2f and LC3f and the fast heavy chains HCIIa and HCIIb respectively. 4. A small fraction of fibres (IIAB), histochemically intermediate between types IIA and IIB, contain the fast light myosin chains but display a coexistence of HCIIa and HCIIb. 5. Similarly to the soleus muscle, C fibres in the tibialis anterior muscle contain both fast and slow myosin light chains and heavy chains. The IIC fibres show a predominance of the fast forms and the IC fibres (histochemically intermediate between types I and IIC) a predominance of the slow forms. 6. A total of 60 ...
Title: Regulatory Light Chains of Striated Muscle Myosin. Structure, Function and Malfunction. VOLUME: 3 ISSUE: 2. Author(s):Danuta Szczesna-Cordary. Affiliation:Department of Molecular&Cellular Pharmacology, University of Miami School of MedicineRosenstiel Medical Sciences Building R-189, Room 6113, USA. Keywords:regulatory light chains of myosin (rlc), Phosphorylation, skinned fibers, familial hypertrophic, cardiomyopathy (fhc) mutations.. Abstract: Striated (skeletal and cardiac) muscle is activated by the binding of Ca2+ to troponin C and is regulated by the thin filament proteins, tropomyosin and troponin. Unlike in molluscan or smooth muscles, the myosin regulatory light chains (RLC) of striated muscles do not play a major regulatory role and their function is still not well understood. The N-terminal domain of RLC contains a Ca2+-Mg2+-binding site and, analogous to that of smooth muscle myosin, also contains a phosphorylation site. During muscle contraction, the increase in Ca2+ ...
The global cell movements that shape an embryo are driven by intricate changes to the cytoarchitecture of individual cells. In a developing embryo, these changes are controlled by patterning genes that confer cell identity. However, little is known about how patterning genes influence cytoarchitecture to drive changes in cell shape. In this paper, we analyze the function of the folded gastrulation gene (fog), a known target of the patterning gene twist. Our analysis of fog function therefore illuminates a molecular pathway spanning all the way from patterning gene to physical change in cell shape. We show that secretion of Fog protein is apically polarized, making this the earliest polarized component of a pathway that ultimately drives myosin to the apical side of the cell. We demonstrate that fog is both necessary and sufficient to drive apical myosin localization through a mechanism involving activation of myosin contractility with actin. We determine that this contractility driven form of ...
In smooth muscle cells (SMCs) isolated from rabbit carotid, femoral, and saphenous arteries, relative myosin isoform mRNA levels were measured in RT-PCR to test for correlations between myosin isoform expression and unloaded shortening velocity. Unloaded shortening velocity and percent smooth muscle myosin heavy chain 2 (SM2) and myosin light chain 17b (MLC17b) mRNA levels were not significantly different in single SMCs isolated from the luminal and adluminal regions of the carotid media. Saphenous artery SMCs shortened significantly faster (P | 0.05) than femoral SMCs and had more SM2 mRNA (P | 0.05) than carotid SMCs and less MLC17b mRNA (P | 0.001) and higher tissue levels of SMB mRNA (P | 0.05) than carotid and femoral SMCs. No correlations were found between percent SM2 and percent MLC17b mRNA levels and unloaded shortening velocity in SMCs from these arteries. We have previously shown that myosin heavy chain (MHC) SM1/SM2 and SMA/SMB and MLC17a/MLC17b isoform mRNA levels correlate with protein
Although cytoskeletal proteins such as myosin II are implicated in the control of insulin secretion, their precise role is poorly understood. In other secretory cells, myosin II is predominantly regulated via the phosphorylation of the regulatory light chains (RLC). The current study was aimed at investigating RLC phosphorylation in beta-cells. In both the insulin-secreting cell line RINm5F and rat pancreatic islets, the RLC was basally phosphorylated on the myosin light chain kinase sites (Ser19/Thr18). Phosphorylation at these sites was not consistently increased by either metabolic stimuli (glyceraldehyde/glucose) or the depolarizing agent KCl. The RLC sites phosphorylated by protein kinase C (PKC) (Ser1/Ser2) were unphosphorylated in the basal state, not affected by nutrients or KCl, and only slightly increased by the PKC activator phorbol 12-myristate 13-acetate (PMA). Like the other insulin secretagogues, however, PMA did promote serine phosphorylation of the myosin heavy chain (MHC) in RINm5F
Centrosomes are the main microtubule (MT)-organizing centers in animal cells, but they also influence the actin/myosin cytoskeleton. The Drosophila CP190 protein is nuclear in interphase, interacts with centrosomes during mitosis, and binds to MTs directly in vitro. CP190 has an essential function in the nucleus as a chromatin insulator, but centrosomes and MTs appear unperturbed in Cp190 mutants. Thus, the centrosomal function of CP190, if any, is unclear. Here, we examine the function of CP190 in Cp190 mutant germline clone embryos. Mitosis is not perturbed in these embryos, but they fail in axial expansion, an actin/myosin-dependent process that distributes the nuclei along the anterior-to-posterior axis of the embryo. Myosin organization is disrupted in these embryos, but actin appears unaffected. Moreover, a constitutively activated form of the myosin regulatory light chain can rescue the axial expansion defect in mutant embryos, suggesting that CP190 acts upstream of myosin activation. A CP190
There are no specific protocols for Anti-Myosin Phosphatase 1+Myosin Phosphatase 2 antibody [YE336] (ab32519). Please download our general protocols booklet
Arterial vascular smooth muscle cells (VSMCs) play an important role in the function of many organ systems. Abnormality in the contractile and/or regulatory apparatus of smooth muscle is implicated in the pathogenesis of a variety of disease conditions such as hypertension, coronary and cerebral vasospasm, miscarriage, and erectile dysfunction. VSMCs in vivo show remarkable plasticity once they need to adapt to changes in environments, such as new development of vasculature and remodeling after vascular injury or during vascular diseases like arteriosclerosis (Owens, 1995). These arterial cells undergo rapid changes in shape and functional property from non-proliferative and contractile to proliferative and mobile phenotype.. Agonist stimulation of VSMCs induces phosphorylation of the 20 kDa regulatory light chain of myosin (MLC), which increases actin-activated myosin ATPase activity and contraction (Hartshorne, 1987; Somlyo and Somlyo, 2003). MLC phosphorylation is governed by the opposing ...
TY - JOUR. T1 - Myosin II is involved in the production of constitutive transport vesicles from the TGN. AU - Müsch, Anne. AU - Cohen, David. AU - Rodriguez-Boulan, Enrique. PY - 1997/7/28. Y1 - 1997/7/28. N2 - The participation of nonmuscle myosins in the transport of organelles and vesicular carriers along actin filaments has been documented. In contrast, there is no evidence for the involvement of myosins in the production of vesicles involved in membrane traffic. Here we show that the putative TGN coat protein p200 (Narula, N., I. McMorrow, G. Plopper, J. Doherty, K.S. Matlin, B. Burke, and J.L. Stow. 1992. J. Cell Biol. 114: 1113- 1124) is myosin II. The recruitment of myosin II to Golgi membranes is dependent on actin and is regulated by G proteins. Using an assay that studies the release of transport vesicles from the TGN in vitro we provide functional evidence that p200/myosin is involved in the assembly of basolateral transport vesicles carrying vesicular stomatitis virus G protein ...
Sheep polyclonal fast skeletal Myosin antibody validated for WB, IP, ELISA, IHC, Neut, ICC/IF and tested in Human, Mouse, Rat and Rabbit. Immunogen…
Toxoplasma gondii is an obligate intracellular parasite that enters cells by a process of active penetration. Host cell penetration and parasite motility are driven by a myosin motor complex consisting of four known proteins: TgMyoA, an unconventional Class XIV myosin; TgMLC1, a myosin light chain; and two membrane-associated proteins, TgGAP45 and TgGAP50. Little is known about how the activity of the myosin motor complex is regulated. Here, we show that treatment of parasites with a recently identified small-molecule inhibitor of invasion and motility results in a rapid and irreversible change in the electrophoretic mobility of TgMLC1. While the precise nature of the TgMLC1 modification has not yet been established, it was mapped to the peptide Val46-Arg59. To determine if the TgMLC1 modification is responsible for the motility defect observed in parasites after compound treatment, the activity of myosin motor complexes from control and compound-treated parasites was compared in an in vitro ...
Cytokinesis is the process by which a cell partitions its surface and cytoplasm to form two daughter cells. In both animal and yeast cells, this process involves the assembly and contraction of an actomyosin ring. It is noteworthy that for a long time, among the hundreds of myosins known, only the conventional myosins of class II had been implicated in cell division (Field et al., 1999). However, a recent study established the involvement of two myosins of type V in S. pombe (Win et al., 2001). The asexual multiplication of T. gondii occurs by a peculiar process named endodyogeny, which is defined as the gradual development of two daughter parasites within a fully differentiated mother; the mother is incorporated into the daughters during the process (Fig. 1). In T. gondii, actin inhibitors did not prevent replication, per se, but disrupted the inheritance of mother cell organelles, resulting in the formation of residual bodies (Shaw et al., 2000). Therefore, myosin motor(s) were anticipated to ...
anti-Myosin Regulatory Light Chain 2, Smooth Muscle Isoform (MYL9) (pThr19), (AA 10-25) antibody (Cy5.5) ABIN753243 from antibodies-online
BACKGROUND: In contrast to conventional muscle myosins, where two different light chains (LCs) stabilize the elongated regulatory domain (RD) region of the head portion of the molecule, unconventional myosins are a diverse group of motors in which from one to six calmodulin (CaM) subunits are bound tandemly to the RD. In both cases, the heavy chains of the RDs have special sequences called "IQ motifs to which the LCs or CaM bind. A previously puzzling aspect of certain unconventional myosins is their unusual mode of regulation, where activation of motility occurs at low levels of Ca2+. Although the atomic structure of the conventional muscle myosin RD has been determined, no crystallographic structure of the RD of an unconventional myosin is yet available. RESULTS: We have constructed a model of vertebrate CaM bound to the first IQ motif present in the neck region of an unconventional myosin (chicken brush border myosin I), using strict binding rules derived from the crystal structure of the ...
A monomeric myosin first spotted in electron micrographs almost 30 years ago has finally been united with a proposed function. Tyska and Mooseker (page 395) report that myosin-1A associates with and anchors a raft component in apical membranes.. Myosin-1A was previously thought to shuttle Golgi-derived cargos to the plasma membrane (after most of the distance had been covered using microtubule-based motors). But the in vitro evidence for this came from undifferentiated cells, and in mature, polarized colon epithelial cells, Tyska and Mooseker see no evidence of shuttling by myosin-1A. What they did spot was cofractionation and cross-linking of myosin-1A with the transmembrane disaccharidase sucrase-isomaltase (SI). This raft protein is lost from the apical surface when a fragment of either myosin-1A or SI interferes with the link between the two full-length proteins.. Thus, myosin-1A may serve as an anchor, with the clustering of SI in rafts helping to secure the link even if an individual ...
We studied the effect of chronic mechanical overloading on the isoenzyme composition of rat cardiac myosin in several experimental models: aortic stenosis (AS), aortic incompetence (AI), aortocaval fistula (ACF), overload of the non-infarcted area after left coronary ligation (INF), and overload of the spontaneously hypertensive rats (SHR). Samples of the left and right ventricles were isolated from these hearts, and myosins were analyzed by electrophoresis in non-dissociating conditions. The myosin isoenzymes were called V1, V2, and V3 in order of decreasing mobility, according to the nomenclature of Hoh et al. Controls of the Wistar and Wistar Kyoto (WKY) strains were almost exclusively V1, A slow age-dependent shift toward V3 was observed in the left ventricles of adult Wistar rats, which at 30 weeks of age (body weight 600 g) contained approximately 15% of this form. In all models of cardiac hypertrophy, an isoenzymic redistribution was observed with a significant increase in V3. The level ...
Define myosin. myosin synonyms, myosin pronunciation, myosin translation, English dictionary definition of myosin. n. Any of a class of proteins that bind with actin filaments and generate many kinds of cell movement, especially the contraction of myofibrils in muscle...
Anti-Myosin VI polyclonal antibody (STJ96437) was developed using a synthesized peptide derived from the N-terminal region of human Myosin VI at AA range: 40-120. This antibody is applicable for use in western blot, immunohistochemistry-P, ELISA and immun
Recent biochemical studies of p190, a calmodulin (CM)-binding protein purified from vertebrate brain, have demonstrated that this protein, purified as a complex with bound CM, shares a number of properties with myosins (Espindola, F. S., E. M. Espreafico, M. V. Coelho, A. R. Martins, F. R. C. Costa, M. S. Mooseker, and R. E. Larson. 1992. J. Cell Biol. 118:359-368). To determine whether or not p190 was a member of the myosin family of proteins, a set of overlapping cDNAs encoding the full-length protein sequence of chicken brain p190 was isolated and sequenced. Verification that the deduced primary structure was that of p190 was demonstrated through microsequence analysis of a cyanogen bromide peptide generated from chick brain p190. The deduced primary structure of chicken brain p190 revealed that this 1,830-amino acid (aa) 212,509-D) protein is a member of a novel structural class of unconventional myosins that includes the gene products encoded by the dilute locus of mouse and the MYO2 gene ...
Purification of native myosin filaments from muscle.: Analysis of the structure and function of native thick (myosin-containing) filaments of muscle has been ha
Results:. Patients with acute aortic dissection who presented within 3 hours after onset had elevated levels of circulating smooth-muscle myosin heavy-chain protein. In these patients, the assay had a sensitivity of 90.9%, a specificity of 98% compared with healthy volunteers, and a specificity of 83% compared with patients who had acute myocardial infarction; the clinical decision limit was 2.5 µg/L. All patients with proximal lesions had elevated levels of smooth-muscle myosin heavy-chain protein, and only patients with distal lesions had decreased levels (,2.5 µg/L). ...
Myosin-1, also known as striated muscle myosin heavy chain 1, is a protein that in humans is encoded by the MYH1 gene. This gene is most highly expressed in fast type IIX/D muscle fibres of vertebrates and encodes a protein found uniquely in striated muscle; it is a class II myosin with a long coiled coil tail that dimerizes and should not be confused with Myosin 1 encoded by the MYO1 family of genes (MYO1A-MYO1H). Class I MYO1 genes function in many cell types throughout biology and are single-headed membrane-binding myosins that lack a long coiled coil tail. Myosin is a major contractile protein that converts chemical energy into mechanical energy through the hydrolysis of ATP. Class II Myosins are hexameric proteins composed of a pair of myosin heavy chains (MYH) and two pairs of nonidentical light chains. Myosin heavy chains are encoded by a multigene family. In mammals, at least ten different myosin heavy chain (MYH) isoforms have been described from striated, smooth, but rarely in ...
Muscle contraction involves the interaction of the myosin heads of the thick filaments with actin subunits of the thin filaments. Relaxation occurs when this interaction is blocked by molecular switches on these filaments. In many muscles, myosin-linked regulation involves phosphorylation of the myosin regulatory light chains (RLCs). Electron microscopy of vertebrate smooth muscle myosin molecules (regulated by phosphorylation) has provided insight into the relaxed structure, revealing that myosin is switched off by intramolecular interactions between its two heads, the free head and the blocked head. Three-dimensional reconstruction of frozen-hydrated specimens revealed that this asymmetric head interaction is also present in native thick filaments of tarantula striated muscle. Our goal in this study was to elucidate the structural features of the tarantula filament involved in phosphorylation-based regulation. A new reconstruction revealed intra- and intermolecular myosin interactions in ...
Myo15 encodes myosin XV (alternatively, Myosin XVa), a 3,511 amino acid member of the unconventional myosin family. Myosin XV has a proline-rich N-terminal extension that does not have sequence similarity to reported proteins and the function is unknown [Figure 3; amino acids 1-1200; SMART; (1-3)]. Myosin XV has a highly conserved motor domain (amino acids 1200-1884; NM_010862; SMART) following the N-terminal extension (2). The motor domain contains an adenosine triphosphate (ATP)- and an actin-binding site (amino acids 1299-1306 and 1776-1783, respectively; Uniprot) (4-6). The myosin neck region contains a variable number of light-chain binding (IQ) motifs (IQxxxRGxxxRK) and is linked to the motor domain by a converter region [(7); reviewed in (8;9)]. Myosin XV has two IQ motifs (amino acids 1909-1920; LQRCLRGFFIKR and amino acids 1932-1943; LQSRARGYLARQ) (5;8;9). The IQ motif is an α-helical structure that often mediates the binding of myosins to calmodulin, members of the EF-hand family of ...
Each myofibril consists of a large number of sarcomeres, the muscle cells smallest functional units.. Each sarcomere consists of a Z-disc in each end and an A-band in the middle. Actin filaments attached to the Z-discs and myosin filaments form the A band. It is the repetitive A-bands that give the characteristic transverse muscle strips seen under a microscope.. Actin and myosin filaments are organised so every myosin filament is surrounded by six actin filaments. The muscle contraction is a result of myosin filaments climbing on actin filaments in each sarcomere.. The actin filaments comprise of several spherical proteins in long helical chains. They consist of the proteins actin, tropomyocin and a troponin complex. All these are essential for muscle contraction.. The myosin filaments are an accumulation of approximately 300 elongated myosin molecules. Each of these proteins has a head on one end. The myosin heads function is to bind and slide on the actin filaments that lie parallel. As ...
A growing body of evidence suggests that myosin heads are dynamically recruited to the thin filaments via mechanisms that displace myosin from the thick filament backbone and toward actin. The earliest evidence of such a process was the inference from x-ray diffraction patterns that there is a transfer of molecular mass from thick to thin filaments during the activation of muscle contraction (Haselgrove and Huxley, 1973). Although such a phenomenon could, in part, be a simple manifestation of myosin head binding to actin, the transfer of mass is observed even at long sarcomere lengths at which there is little overlap of thick and thin filaments and therefore little binding of myosin heads to actin. This apparent activation of head displacement is a puzzling but potentially important aspect of muscle contraction because movement of myosin heads closer to actin would presumably increase the probability of binding to actin and increase the rate and amplitude of force development. Recent work ...
DNA fragments located 10 kilobases apart in the genome and containing, respectively, the first myosin light chain 1 (MLC1f) and the first myosin light chain 3 (MLC3f) specific exon of the rat myosin light chain 1 and 3 gene, together with several hundred base pairs of upstream flanking sequences, have been shown in runoff in vitro transcription assays to direct initiation of transcription at the cap sites of MLC1f and MLC3f mRNAs used in vivo. These results establish the presence of two separate, functional promoters within that gene. A comparison of the nucleotide sequence of the rat MLC1f/3f gene with the corresponding sequences from mouse and chicken shows that: the MLC1f promoter regions have been highly conserved up to position -150 from the cap site while the MLC3f promoter regions display a very poor degree of homology and even the absence or poor conservation of typical eucaryotic promoter elements such as TATA and CAT boxes; the exon/intron structure of this gene has been completely conserved
for the thin filaments on either side of the Z disc 8. Muscle contraction: sarcomere will shorten in length as Z discs come closer together and size of the H band decreases; the thin filaments are overlapping the thick filaments. 9. Sliding filament hypothesis: (1). Myosin heads bind ATP and split it forming ADP and Pi (2). Myosin heads bind to sites on the actin filaments (3). Myosin heads release the Pi allowing the head to bend toward the A band and Pulling the actin filaments with it; this is the power stroke (4).At end of power stroke, myosin head binds a new ATP and releases ADP; myosin head breaks away from the actin filament 10. Cross bridges: temporary union between the myosin and actin filaments 11. Troponin: protein that binds tropomyosin to actin; also is attracted to Ca+2 ions Tropomyosin: double strand of protein; blocks actin binding sites preventing myosin attachment 12. Neuromuscular junction: (1). Neuron releases acetylcholine which binds to Ach receptors on motor end Plate of ...
TY - JOUR. T1 - Characterization of single actin-myosin interactions. AU - Finer, J. T.. AU - Mehta, A. D.. AU - Spudich, J. A.. AU - Lombardi, V.. AU - Kinosita, K.. AU - Block, S.. AU - Gilford, [No Value]. AU - Cooke, R.. AU - Brenner, B.. AU - Highsmith, S.. PY - 1995. Y1 - 1995. N2 - The feedback-enhanced laser trap assay (Finer et al., 1994) allows the measurement of force and displacement produced by single myosin molecules interacting with an actin filament suspended in solution by two laser traps. The average displacement of 11 nm at low lead and the average force of 4 pN near isometric conditions are consistent with the conventional swinging cross-bridge model of muscle contraction (Huxley, 1969). The durations of single actin-myosin interactions at low lead, 3-7 ms, suggest a relatively small duty ratio. Event durations can be increased either by reducing the ATP concentration until ATP binding is rate-limiting or by lowering the temperature. For sufficiently long interactions near ...
Buy anti-PRKDC antibody, Rabbit Myosin Light Chain 2 Polyclonal Antibody-NP_001075109.1 (MBS857334) product datasheet at MyBioSource, Primary Antibodies. Application: Immunohistochemistry (IHC)
FUNCTION: [Summary is not available for the mouse gene. This summary is for the human ortholog.] This gene encodes a member of the myosin superfamily. The protein represents an unconventional myosin; it should not be confused with the conventional non-muscle myosin-9 (MYH9). Unconventional myosins contain the basic domains of conventional myosins and are further distinguished from class members by their tail domains. They function as actin-based molecular motors. Mutations in this gene have been associated with Bardet-Biedl Syndrome. [provided by RefSeq, Dec 2011 ...
ERM proteins bind the Na+/H+ exchanger regulatory factor‐1, 2 (NHERF‐1 and ‐2), which are key cytoplasmic proteins involved in the anchoring of ion channels and receptors to the actin cytoskeleton through binding to ERM proteins. These adaptor proteins preserve FERM‐binding Motif‐2 (MDWxxxxx(L/I)Fxx(L/F)) and form an α‐helix that docks into the groove formed by the β‐sandwich loops of subdomain C (Terawaki et al, 2006), which displays no similarity to the DCC/neogenin P3 motif (Figure 6C). The myosin‐X FERM domain lacks the PtdIns(4,5)P2‐binding site found in the radixin FERM domain as previously described (Figure 6D).. It was one of the most exciting findings in cell biology of cytoskeletons that myosin‐X has the ability to function as a motorized link between actin filaments and microtubules in spindle assembly during meiosis (Weber et al, 2004; Toyoshima and Nishida, 2007; Woolner et al, 2008). However, to date, only a single report of Xenopus myosin‐X has shown the ...
25 a ON OFF b MUTIPLE CROSS BRIDGES Q) u c S(/) "0 SINGLE CROSS BRIDGE time Fig. 6. A: Diagram of crossbridge cycle. Each crossbridge repeats attachment and detachment cycle. B: Sliding movement of bead driven by single and multiple crossbridges. In summary, we have utilized in vitro motility assay techniques to study the mechanical property of cardiac myosin under various conditions for different myosin isoforms. Although these findings were anticipated based on previous experiments with muscle preparations, this is the first presentation of such direct evidence at the molecular level. 13. J. Thyroxine induced redistribution of isozyme of rabbit ventricular myosin. Circ Res 50: 117 -124, 1982. 14. , et. al. Dynamic interaction between cardiac myosin isoforms modifies velocity of actomyosin sliding in vitro. Circ Res 73:696-704, 1993. 27 15. Barany, M. ATPase activity of myosin correlated with speed of muscle shortening. J Gen Physiol 50:197-218, 1967. 16. , Poggesi, C. et. al. Shortening ...
The Drosophila body axes are established in the oocyte during oogenesis. Oocyte polarization is initiated by Gurken, which signals from the germline through the epidermal growth factor receptor (Egfr) to the posterior follicle cells (PFCs). In response the PFCs generate an unidentified polarizing signal that regulates oocyte polarity. We have identified a loss-of-function mutation of flapwing, which encodes the catalytic subunit of Protein Phosphatase 1β (PP1β) that disrupts oocyte polarization. We show that PP1β, by regulating myosin activity, controls the generation of the polarizing signal. Excessive myosin activity in the PFCs causes oocyte mispolarization and defective Notch signaling and endocytosis in the PFCs. The integrated activation of JAK/STAT and Egfr signaling results in the sensitivity of PFCs to defective Notch. Interestingly, our results also demonstrate a role of PP1β in generating the polarizing signal independently of Notch, indicating a direct involvement of somatic ...
The vertebrate genetic locus, coding for a Ca2+/calmodulin-dependent enzyme myosin light chain kinase (MLCK), the key regulator of smooth muscle contraction and cell motility, reveals a complex organization. Two MLCK isoforms are encoded by the MLCK genetic locus. Recently identified M(r) 210 kDa MLCK contains a sequence of smooth muscle/non-muscle M(r) 108 kDa MLCK and has an additional N-terminal sequence (Watterson et al., 1995. FEBS Lett. 373 : 217). A gene for an independently expressed non-kinase product KRP (telokin) is located within the MLCK gene (Collinge et al., 1992. Mol. Cell. Biol. 12 : 2359). KRP binds to and regulates the structure of myosin filaments (Shirinsky et al., 1993. J. Biol. Chem. 268 : 16578). Here we compared biochemical properties of MLCK-210 and MLCK-108 and studied intracellular localization of MLCK-210. MLCK-210 was isolated from extract of chicken aorta by immunoprecipitation using specific antibody and biochemically analysed in vitro. MLCK-210 phosphorylated myosin
Myosin II is a motor protein found in the cytoskeleton in the cytoplasm of cells. It is responsible for enpowering actin to contract. In "[[A quantitative analysis of contractility in active cytoskeletal protein networks]]" by Weitz et al. Show the role of myosin in actin contraction. It was shown that without appropriate amounts of ,math>alpha,/math>-actinin, myosin cannot produce contraction. ==References== http://en.wikipedia.org/wiki/Myosin ...
MYH7 is a gene encoding a myosin heavy chain beta (MHC-β) isoform (slow twitch) expressed primarily in the heart, but also in skeletal muscles (type I fibers). This isoform is distinct from the fast isoform of cardiac myosin heavy chain, MYH6, referred to as MHC-α. MHC-β is the major protein comprising the thick filament in cardiac muscle and plays a major role in cardiac muscle contraction. MHC-β is a 223 kDa protein composed of 1935 amino acids. MHC-β is a hexameric, asymmetric motor forming the bulk of the thick filament in cardiac muscle. MHC-β is composed of N-terminal globular heads (20 nm) that project laterally, and alpha helical tails (130 nm) that dimerize and multimerize into a coiled-coil motif to form the light meromyosin (LMM), thick filament rod. The 9 nm alpha-helical neck region of each MHC-β head non-covalently binds two light chains, essential light chain (MYL3) and regulatory light chain (MYL2). Approximately 300 myosin molecules constitute one thick filament. There ...
Cardiomyopathies (CM) are the leading cause of death in America, and can develop from mutations in sarcomeric proteins, leading to altered protein structure and function. Current therapies target upstream signaling pathways to treat the symptoms of heart failure, but are associated with increased mortality by affecting downstream signaling pathways and other muscle types. Rational drug design can develop therapies to treat CM at the protein level. However, a detailed knowledge of how sarcomeric proteins regulate muscle contraction is required. Muscle contraction occurs through a cyclic interaction between actin thin and myosin thick filaments, regulated by intracellular Ca2+ concentration. Troponin (Tn), the Ca2+-binding protein in muscle, allosterically regulates actin and myosin interactions (crossbridge formation) by facilitating the release of two troponin I (TnI) actin binding sites at high Ca2+, the inhibitory region (IR) and the second actin binding site (SABS). The mechanism to remove TnI
antibody against myosin heavy chain, embryonic and adult fast expressed by for use in Immunohistochemistry against Chicken, Fish, Xenopus, Zebrafish
We are examining the force-sensitivity of Acanthamoeba myosin 1c (AM1C) activity. Class 1 myosins have been split into two subclasses. While subclass 2 myosins are hypothesized to have a force-dependent activity, subclass 1 myosins are not. Two subclass 2 myosins (Rat Myo1b and Mouse Myo1c) have been shown to have a high degree of force-sensitivity, but no subclass 1 myosin has yet been tested. To test the force sensitivity of AM1C, which is from subclass 1, we are using an optical trap, which allows us to apply picoNewton forces to single myosin motors. ...