Proteins which bind calmodulin. They are found in many tissues and have a variety of functions including F-actin cross-linking properties, inhibition of cyclic nucleotide phosphodiesterase and calcium and magnesium ATPases.
A heat-stable, low-molecular-weight activator protein found mainly in the brain and heart. The binding of calcium ions to this protein allows this protein to bind to cyclic nucleotide phosphodiesterases and to adenyl cyclase with subsequent activation. Thereby this protein modulates cyclic AMP and cyclic GMP levels.
A phenothiazine with actions similar to CHLORPROMAZINE. It is used as an antipsychotic and an antiemetic.
A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.
The parts of a macromolecule that directly participate in its specific combination with another molecule.
An enzyme that phosphorylates myosin light chains in the presence of ATP to yield myosin-light chain phosphate and ADP, and requires calcium and CALMODULIN. The 20-kDa light chain is phosphorylated more rapidly than any other acceptor, but light chains from other myosins and myosin itself can act as acceptors. The enzyme plays a central role in the regulation of smooth muscle contraction.
Proteins to which calcium ions are bound. They can act as transport proteins, regulator proteins, or activator proteins. They typically contain EF HAND MOTIFS.
A nervous tissue specific protein which is highly expressed in NEURONS during development and NERVE REGENERATION. It has been implicated in neurite outgrowth, long-term potentiation, SIGNAL TRANSDUCTION, and NEUROTRANSMITTER release. (From Neurotoxicology 1994;15(1):41-7) It is also a substrate of PROTEIN KINASE C.
The rate dynamics in chemical or physical systems.
Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.
A subclass of myosins found generally associated with actin-rich membrane structures such as filopodia. Members of the myosin type I family are ubiquitously expressed in eukaryotes. The heavy chains of myosin type I lack coiled-coil forming sequences in their tails and therefore do not dimerize.
A BRAIN-specific substrate for PROTEIN KINASE C that binds CALMODULIN and is involved in regulation of CALCIUM SIGNALING.
The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.
Cation-transporting proteins that utilize the energy of ATP hydrolysis for the transport of CALCIUM. They differ from CALCIUM CHANNELS which allow calcium to pass through a membrane without the use of energy.
Proteins that bind to the 3' polyadenylated region of MRNA. When complexed with RNA the proteins serve an array of functions such as stabilizing the 3' end of RNA, promoting poly(A) synthesis and stimulating mRNA translation.

Adducin polymorphism affects renal proximal tubule reabsorption in hypertension. (1/1442)

Abnormalities in renal sodium reabsorption may be involved in the development and maintenance of experimental and clinical hypertension. Adducin polymorphism is thought to regulate ion transport in the renal tubule. It has recently been shown that there is a significant linkage of alpha-adducin locus to essential hypertension and that the 460Trp allele is associated with hypertension. Patients with this allele display larger blood pressure changes with body sodium variation. The aim of this study was to test whether alpha-adducin polymorphism is involved in abnormalities of renal function. Because proximal tubular reabsorption has been shown to be tightly coupled to renal perfusion pressure, this segmental tubular function was investigated in 54 (29 Gly/Gly and 25 Gly/Trp) untreated hypertensive patients in basal conditions with the use of endogenous lithium concentration and uric acid. Fractional excretions of lithium and uric acid were significantly decreased in the Gly/Trp hypertensive patients compared with the Gly/Gly hypertensives. The contribution of alpha-adducin to fractional excretion of lithium was investigated by multiple regression analysis. Adducin genotype was significantly (R2=0.11, F=6.5; P<0.01) and directly related to fraction excretion of lithium; gender, age, urinary Na+, urinary uric acid, mean blood pressure, and plasma renin activity were not related. In conclusion, the adducin gene can be considered to be a 'renal hypertensive gene' that modulates the capacity of tubular epithelial cells to transport Na+ and hence contributes to the level of blood pressure.  (+info)

PST 2238: A new antihypertensive compound that modulates Na,K-ATPase in genetic hypertension. (2/1442)

A genetic alteration in the adducin genes is associated with hypertension and up-regulation of the expression of renal Na, K-ATPase in Milan-hypertensive (MHS) rats, in which increased ouabain-like factor (OLF) levels are also observed. PST 2238, a new antihypertensive compound that antagonizes the pressor effect of ouabain in vivo and normalizes ouabain-dependent up-regulation of the renal Na-K pump, was evaluated for its ability to lower blood pressure and regulate renal Na,K-ATPase activity in MHS genetic hypertension. In this study, we show that PST 2238, given orally at very low doses (1 and 10 microg/kg for 5-6 weeks), reduced the development of hypertension in MHS rats and normalized the increased renal Na,K-ATPase activity and mRNA levels, whereas it did not affect either blood pressure or Na,K-ATPase in Milan-normotensive (MNS) rats. In addition, a similar antihypertensive effect was observed in adult MHS rats after a short-term treatment. In cultured rat renal cells with increased Na-K pump activity at Vmax due to overexpression of the hypertensive variant of adducin, 5 days of incubation with PST 2238 (10(-10-)-10(-9) M) lowered the pump rate to the level of normal wild-type cells, which in turn were not affected by the drug. In conclusion, PST 2238 is a very potent compound that in MHS rats reduces blood pressure and normalizes Na-K pump alterations caused by a genetic alteration of the cytoskeletal adducin. Because adducin gene mutations have been associated with human essential hypertension, it is suggested that PST 2238 may display greater antihypertensive activity in those patients carrying such a genetic alteration.  (+info)

Transcriptional down-regulation of the rabbit pulmonary artery endothelin B receptor during phenotypic modulation. (3/1442)

1. We confirmed that endothelium-independent contraction of the rabbit pulmonary artery (RPA) is mediated through both an endothelin A (ET(A)R) and endothelin B (ET(B2)R) receptor. 2. The response of endothelium-denuded RPA rings to endothelin-1 (ET-1, pD2 = 7.84 +/- 0.03) was only partially inhibited by BQ123 (10 microM), an ET(A)R antagonist. 3. Pretreatment with 1 nM sarafotoxin S6c (S6c), an ET(B)R agonist, desensitized the ET(B2)R and significantly attenuated the response to ET-3 (pD2 = 7.40 +/- 0.02 before, <6.50 after S6c). 4. Pretreatment with S6c had little effect on the response to ET-1, but BQ123 (10 microM) caused a parallel shift to the right of the residual ETAR-mediated response to ET-1 (pD2 = 7.84 +/- 0.03 before S6c, 7.93 +/- 0.03 after S6c, 6.81 +/- 0.05 after BQ123). 5. Binding of radiolabelled ET-1 to early passage cultures of RPA vascular smooth muscle cells (VSMC) displayed two patterns of competitive displacement characteristic of the ET(A)R (BQ123 pIC50 = 8.73 +/- 0.05) or ET(B2)R (S6c pIC50 = 10.15). 6. Competitive displacement experiments using membranes from late passage VSMC confirmed only the presence of the ET(A)R (ET-1 pIC50 = 9.3, BQ123 pIC50 = 8.0, S6c pIC50 < 6.0). 7. The ET(A)R was functionally active and coupled to rises in intracellular calcium which exhibited prolonged homologous desensitization. 8. Using a reverse transcriptase polymerase chain reaction for the rabbit ET(B2)R, we demonstrated the absence of mRNA expression in phenotypically modified VSMC. 9. We conclude that the ET(B2)R expressed by VSMC which mediates contraction of RPA is rapidly down-regulated at the transcriptional level during phenotypic modulation in vitro.  (+info)

Interactions between neurogranin and calmodulin in vivo. (4/1442)

Neurogranin is a neural-specific, calmodulin (CaM)-binding protein that is phosphorylated by protein kinase C (PKC) within its IQ domain at serine 36. Since CaM binds to neurogranin through the IQ domain, PKC phosphorylation and CaM binding are mutually exclusive. Consequently, we hypothesize that neurogranin may function to concentrate CaM at specific sites in neurons and release free CaM in response to increased Ca2+ and PKC activation. However, it has not been established that neurogranin interacts with CaM in vivo. In this study, we examined this question using yeast two-hybrid methodology. We also searched for additional proteins that might interact with neurogranin by screening brain cDNA libraries. Our data illustrate that CaM binds to neurogranin in vivo and that CaM is the only neurogranin-interacting protein isolated from brain cDNA libraries. Single amino acid mutagenesis indicated that residues within the IQ domain are important for CaM binding to neurogranin in vivo. The Ile-33 --> Gln point mutant completely inhibited and Arg-38 --> Gln and Ser-36 --> Asp point mutants reduced neurogranin/CaM interactions. These data demonstrate that CaM is the major protein that interacts with neurogranin in vivo and support the hypothesis that phosphorylation of neurogranin at Ser-36 regulates its binding to CaM.  (+info)

Mechanical and chemical unfolding of a single protein: a comparison. (5/1442)

Is the mechanical unraveling of protein domains by atomic force microscopy (AFM) just a technological feat or a true measurement of their unfolding? By engineering a protein made of tandem repeats of identical Ig modules, we were able to get explicit AFM data on the unfolding rate of a single protein domain that can be accurately extrapolated to zero force. We compare this with chemical unfolding rates for untethered modules extrapolated to 0 M denaturant. The unfolding rates obtained by the two methods are the same. Furthermore, the transition state for unfolding appears at the same position on the folding pathway when assessed by either method. These results indicate that mechanical unfolding of a single protein by AFM does indeed reflect the same event that is observed in traditional unfolding experiments. The way is now open for the extensive use of AFM to measure folding reactions at the single-molecule level. Single-molecule AFM recordings have the added advantage that they define the reaction coordinate and expose rare unfolding events that cannot be observed in the absence of chemical denaturants.  (+info)

Identification of chURP, a nuclear calmodulin-binding protein related to hnRNP-U. (6/1442)

In a screen for myosin-like proteins in embryonic chicken brain, we have identified a novel nuclear protein structurally related to hnRNP-U (heterogeneous nuclear ribonuclear protein U). We have called this protein chURP, for chicken U-related protein. In this screen, chURP was immunoreactive with two myosin antibodies and, in common with the unconventional myosins, bound calmodulin in vitro in both the presence and absence of calcium ions. Determination of 757 amino acids of the chURP sequence revealed that it shares 41% amino acid identity with human and rat hnRNP-U, although chURP and hnRNP-U appear not to be orthologous proteins. ChURP is ubiquitously expressed in the nuclei of all chick tissues and, as one of a growing number of calmodulin-binding proteins to be identified in the nucleus, further highlights the potential of calmodulin as a regulator of nuclear metabolism.  (+info)

Identification of the calmodulin-binding domain of neuron-specific protein kinase C substrate protein CAP-22/NAP-22. Direct involvement of protein myristoylation in calmodulin-target protein interaction. (7/1442)

Various proteins in the signal transduction pathways as well as those of viral origin have been shown to be myristoylated. Although the modification is often essential for the proper functioning of the modified protein, the mechanism by which the modification exerts its effects is still largely unknown. Brain-specific protein kinase C substrate, CAP-23/NAP-22, which is involved in the synaptogenesis and neuronal plasticity, binds calmodulin, but the protein lacks any canonical calmodulin-binding domain. In the present report, we show that CAP-23/NAP-22 isolated from rat brain is myristoylated and that the modification is directly involved in its interaction with calmodulin. Myristoylated and non-myristoylated recombinant proteins were produced in Escherichia coli, and their calmodulin-binding properties were examined. Only the former bound to calmodulin. Synthetic peptides based on the N-terminal sequence showed similar binding properties to calmodulin, only when they were myristoylated. The calmodulin-binding site narrowed down to the myristoyl moiety together with a nine-amino acid N-terminal basic domain. Phosphorylation of a single serine residue in the N-terminal domain (Ser5) by protein kinase C abolished the binding. Furthermore, phosphorylation of CAP-23/NAP-22 by protein kinase C was also found myristoylation-dependent, suggesting the importance of myristoylation in protein-protein interactions.  (+info)

Phosphorylation of adducin by Rho-kinase plays a crucial role in cell motility. (8/1442)

Adducin is a membrane skeletal protein that binds to actin filaments (F-actin) and thereby promotes the association of spectrin with F-actin to form a spectrin-actin meshwork beneath plasma membranes such as ruffling membranes. Rho-associated kinase (Rho- kinase), which is activated by the small guanosine triphosphatase Rho, phosphorylates alpha-adducin and thereby enhances the F-actin-binding activity of alpha-adducin in vitro. Here we identified the sites of phosphorylation of alpha-adducin by Rho-kinase as Thr445 and Thr480. We prepared antibody that specifically recognized alpha-adducin phosphorylated at Thr445, and found by use of this antibody that Rho-kinase phosphorylated alpha-adducin at Thr445 in COS7 cells in a Rho-dependent manner. Phosphorylated alpha-adducin accumulated in the membrane ruffling area of Madin-Darby canine kidney (MDCK) epithelial cells and the leading edge of scattering cells during the action of tetradecanoylphorbol-13-acetate (TPA) or hepatocyte growth factor (HGF). The microinjection of Botulinum C3 ADP-ribosyl-transferase, dominant negative Rho-kinase, or alpha-adducinT445A,T480A (substitution of Thr445 and Thr480 by Ala) inhibited the TPA-induced membrane ruffling in MDCK cells and wound-induced migration in NRK49F cells. alpha-AdducinT445D,T480D (substitution of Thr445 and Thr480 by Asp), but not alpha-adducinT445A,T480A, counteracted the inhibitory effect of the dominant negative Rho-kinase on the TPA-induced membrane ruffling in MDCK cells. Taken together, these results indicate that Rho-kinase phosphorylates alpha-adducin downstream of Rho in vivo, and that the phosphorylation of adducin by Rho-kinase plays a crucial role in the regulation of membrane ruffling and cell motility.  (+info)

Calmodulin-binding proteins are a diverse group of proteins that have the ability to bind to calmodulin, a ubiquitous calcium-binding protein found in eukaryotic cells. Calmodulin plays a critical role in various cellular processes by regulating the activity of its target proteins in a calcium-dependent manner.

Calmodulin-binding proteins contain specific domains or motifs that enable them to interact with calmodulin. These domains can be classified into two main categories: IQ motifs and CaM motifs. The IQ motif is a short amino acid sequence that contains the consensus sequence IQXXXRGXXR, where X represents any amino acid. This motif binds to the C-lobe of calmodulin in a calcium-dependent manner. On the other hand, CaM motifs are longer sequences that can bind to both lobes of calmodulin with high affinity and in a calcium-dependent manner.

Calmodulin-binding proteins play crucial roles in various cellular functions, including signal transduction, gene regulation, cytoskeleton organization, and ion channel regulation. For example, calmodulin-binding proteins such as calcineurin and CaM kinases are involved in the regulation of immune responses, learning, and memory. Similarly, myosin regulatory light chains, which contain IQ motifs, play a critical role in muscle contraction by regulating the interaction between actin and myosin filaments.

In summary, calmodulin-binding proteins are a diverse group of proteins that interact with calmodulin to regulate various cellular processes. They contain specific domains or motifs that enable them to bind to calmodulin in a calcium-dependent manner, thereby modulating the activity of their target proteins.

Calmodulin is a small, ubiquitous calcium-binding protein that plays a critical role in various intracellular signaling pathways. It functions as a calcium sensor, binding to and regulating the activity of numerous target proteins upon calcium ion (Ca^2+^) binding. Calmodulin is expressed in all eukaryotic cells and participates in many cellular processes, including muscle contraction, neurotransmitter release, gene expression, metabolism, and cell cycle progression.

The protein contains four EF-hand motifs that can bind Ca^2+^ ions. Upon calcium binding, conformational changes occur in the calmodulin structure, exposing hydrophobic surfaces that facilitate its interaction with target proteins. Calmodulin's targets include enzymes (such as protein kinases and phosphatases), ion channels, transporters, and cytoskeletal components. By modulating the activity of these proteins, calmodulin helps regulate essential cellular functions in response to changes in intracellular Ca^2+^ concentrations.

Calmodulin's molecular weight is approximately 17 kDa, and it consists of a single polypeptide chain with 148-150 amino acid residues. The protein can be found in both the cytoplasm and the nucleus of cells. In addition to its role as a calcium sensor, calmodulin has been implicated in various pathological conditions, including cancer, neurodegenerative diseases, and cardiovascular disorders.

Trifluoperazine is an antipsychotic medication that belongs to the class of drugs called phenothiazines. It works by blocking the action of dopamine, a neurotransmitter in the brain, and helps to reduce symptoms of schizophrenia such as hallucinations, delusions, paranoia, and disordered thought. Trifluoperazine may also be used to manage anxiety or agitation in certain medical conditions. It is available in the form of tablets for oral administration. As with any medication, trifluoperazine should be taken under the supervision of a healthcare provider due to potential side effects and risks associated with its use.

Calcium is an essential mineral that is vital for various physiological processes in the human body. The medical definition of calcium is as follows:

Calcium (Ca2+) is a crucial cation and the most abundant mineral in the human body, with approximately 99% of it found in bones and teeth. It plays a vital role in maintaining structural integrity, nerve impulse transmission, muscle contraction, hormonal secretion, blood coagulation, and enzyme activation.

Calcium homeostasis is tightly regulated through the interplay of several hormones, including parathyroid hormone (PTH), calcitonin, and vitamin D. Dietary calcium intake, absorption, and excretion are also critical factors in maintaining optimal calcium levels in the body.

Hypocalcemia refers to low serum calcium levels, while hypercalcemia indicates high serum calcium levels. Both conditions can have detrimental effects on various organ systems and require medical intervention to correct.

Molecular sequence data refers to the specific arrangement of molecules, most commonly nucleotides in DNA or RNA, or amino acids in proteins, that make up a biological macromolecule. This data is generated through laboratory techniques such as sequencing, and provides information about the exact order of the constituent molecules. This data is crucial in various fields of biology, including genetics, evolution, and molecular biology, allowing for comparisons between different organisms, identification of genetic variations, and studies of gene function and regulation.

An amino acid sequence is the specific order of amino acids in a protein or peptide molecule, formed by the linking of the amino group (-NH2) of one amino acid to the carboxyl group (-COOH) of another amino acid through a peptide bond. The sequence is determined by the genetic code and is unique to each type of protein or peptide. It plays a crucial role in determining the three-dimensional structure and function of proteins.

Protein binding, in the context of medical and biological sciences, refers to the interaction between a protein and another molecule (known as the ligand) that results in a stable complex. This process is often reversible and can be influenced by various factors such as pH, temperature, and concentration of the involved molecules.

In clinical chemistry, protein binding is particularly important when it comes to drugs, as many of them bind to proteins (especially albumin) in the bloodstream. The degree of protein binding can affect a drug's distribution, metabolism, and excretion, which in turn influence its therapeutic effectiveness and potential side effects.

Protein-bound drugs may be less available for interaction with their target tissues, as only the unbound or "free" fraction of the drug is active. Therefore, understanding protein binding can help optimize dosing regimens and minimize adverse reactions.

In the context of medical and biological sciences, a "binding site" refers to a specific location on a protein, molecule, or cell where another molecule can attach or bind. This binding interaction can lead to various functional changes in the original protein or molecule. The other molecule that binds to the binding site is often referred to as a ligand, which can be a small molecule, ion, or even another protein.

The binding between a ligand and its target binding site can be specific and selective, meaning that only certain ligands can bind to particular binding sites with high affinity. This specificity plays a crucial role in various biological processes, such as signal transduction, enzyme catalysis, or drug action.

In the case of drug development, understanding the location and properties of binding sites on target proteins is essential for designing drugs that can selectively bind to these sites and modulate protein function. This knowledge can help create more effective and safer therapeutic options for various diseases.

Myosin-Light-Chain Kinase (MLCK) is an enzyme that plays a crucial role in muscle contraction. It phosphorylates the regulatory light chains of myosin, a protein involved in muscle contraction, leading to the activation of myosin and the initiation of the contractile process. MLCK is activated by calcium ions and calmodulin, and its activity is essential for various cellular processes, including cytokinesis, cell motility, and maintenance of cell shape. In addition to its role in muscle contraction, MLCK has been implicated in several pathological conditions, such as hypertension, atherosclerosis, and cancer.

Calcium-binding proteins (CaBPs) are a diverse group of proteins that have the ability to bind calcium ions (Ca^2+^) with high affinity and specificity. They play crucial roles in various cellular processes, including signal transduction, muscle contraction, neurotransmitter release, and protection against oxidative stress.

The binding of calcium ions to these proteins induces conformational changes that can either activate or inhibit their functions. Some well-known CaBPs include calmodulin, troponin C, S100 proteins, and parvalbumins. These proteins are essential for maintaining calcium homeostasis within cells and for mediating the effects of calcium as a second messenger in various cellular signaling pathways.

GAP-43 protein, also known as growth-associated protein 43 or B-50, is a neuronal protein that is highly expressed during development and axonal regeneration. It is involved in the regulation of synaptic plasticity, nerve impulse transmission, and neurite outgrowth. GAP-43 is localized to the growth cones of growing axons and is thought to play a role in the guidance and navigation of axonal growth during development and regeneration. It is a member of the calcium/calmodulin-dependent protein kinase substrate family and undergoes phosphorylation by several protein kinases, including PKC (protein kinase C), which regulates its function. GAP-43 has been implicated in various neurological disorders, such as Alzheimer's disease, Parkinson's disease, and schizophrenia.

In the context of medicine and pharmacology, "kinetics" refers to the study of how a drug moves throughout the body, including its absorption, distribution, metabolism, and excretion (often abbreviated as ADME). This field is called "pharmacokinetics."

1. Absorption: This is the process of a drug moving from its site of administration into the bloodstream. Factors such as the route of administration (e.g., oral, intravenous, etc.), formulation, and individual physiological differences can affect absorption.

2. Distribution: Once a drug is in the bloodstream, it gets distributed throughout the body to various tissues and organs. This process is influenced by factors like blood flow, protein binding, and lipid solubility of the drug.

3. Metabolism: Drugs are often chemically modified in the body, typically in the liver, through processes known as metabolism. These changes can lead to the formation of active or inactive metabolites, which may then be further distributed, excreted, or undergo additional metabolic transformations.

4. Excretion: This is the process by which drugs and their metabolites are eliminated from the body, primarily through the kidneys (urine) and the liver (bile).

Understanding the kinetics of a drug is crucial for determining its optimal dosing regimen, potential interactions with other medications or foods, and any necessary adjustments for special populations like pediatric or geriatric patients, or those with impaired renal or hepatic function.

"Cattle" is a term used in the agricultural and veterinary fields to refer to domesticated animals of the genus *Bos*, primarily *Bos taurus* (European cattle) and *Bos indicus* (Zebu). These animals are often raised for meat, milk, leather, and labor. They are also known as bovines or cows (for females), bulls (intact males), and steers/bullocks (castrated males). However, in a strict medical definition, "cattle" does not apply to humans or other animals.

Myosin Type I, also known as myosin-IA, is a type of motor protein found in non-muscle cells. It is involved in various cellular processes such as organelle transport, cell division, and maintenance of cell shape. Myosin-IA consists of a heavy chain, light chains, and a cargo-binding tail domain. The heavy chain contains the motor domain that binds to actin filaments and hydrolyzes ATP to generate force and movement along the actin filament.

Myosin-I is unique among myosins because it can move in both directions along the actin filament, whereas most other myosins can only move in one direction. Additionally, myosin-I has a high duty ratio, meaning that it spends a larger proportion of its ATP hydrolysis cycle bound to the actin filament, making it well-suited for processes requiring sustained force generation or precise positioning.

Neurogranin is a protein that is primarily found in the postsynaptic density of excitatory neurons in the brain. It is a calmodulin-binding protein and plays a significant role in synaptic plasticity, which is the ability of synapses to strengthen or weaken over time, in response to increases or decreases in their activity. Neurogranin has been identified as a potential biomarker for Alzheimer's disease and other neurodegenerative disorders due to its susceptibility to proteolytic cleavage by enzymes such as caspases, which are activated during apoptosis or programmed cell death. Increased levels of neurogranin fragments in cerebrospinal fluid have been associated with cognitive decline and neurodegeneration in Alzheimer's disease.

Tertiary protein structure refers to the three-dimensional arrangement of all the elements (polypeptide chains) of a single protein molecule. It is the highest level of structural organization and results from interactions between various side chains (R groups) of the amino acids that make up the protein. These interactions, which include hydrogen bonds, ionic bonds, van der Waals forces, and disulfide bridges, give the protein its unique shape and stability, which in turn determines its function. The tertiary structure of a protein can be stabilized by various factors such as temperature, pH, and the presence of certain ions. Any changes in these factors can lead to denaturation, where the protein loses its tertiary structure and thus its function.

Calcium-transporting ATPases, also known as calcium pumps, are a type of enzyme that use the energy from ATP (adenosine triphosphate) hydrolysis to transport calcium ions across membranes against their concentration gradient. This process helps maintain low intracellular calcium concentrations and is essential for various cellular functions, including muscle contraction, neurotransmitter release, and gene expression.

There are two main types of calcium-transporting ATPases: the sarcoplasmic/endoplasmic reticulum Ca^2+^-ATPase (SERCA) and the plasma membrane Ca^2+^-ATPase (PMCA). SERCA is found in the sarcoplasmic reticulum of muscle cells and endoplasmic reticulum of other cell types, where it pumps calcium ions into these organelles to initiate muscle relaxation or signal transduction. PMCA, on the other hand, is located in the plasma membrane and extrudes calcium ions from the cell to maintain low cytosolic calcium concentrations.

Calcium-transporting ATPases play a crucial role in maintaining calcium homeostasis in cells and are important targets for drug development in various diseases, including heart failure, hypertension, and neurological disorders.

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