Amyloid beta-Protein Precursor: A single-pass type I membrane protein. It is cleaved by AMYLOID PRECURSOR PROTEIN SECRETASES to produce peptides of varying amino acid lengths. A 39-42 amino acid peptide, AMYLOID BETA-PEPTIDES is a principal component of the extracellular amyloid in SENILE PLAQUES.Amyloid beta-Peptides: Peptides generated from AMYLOID BETA-PEPTIDES PRECURSOR. An amyloid fibrillar form of these peptides is the major component of amyloid plaques found in individuals with Alzheimer's disease and in aged individuals with trisomy 21 (DOWN SYNDROME). The peptide is found predominantly in the nervous system, but there have been reports of its presence in non-neural tissue.Amyloid: A fibrous protein complex that consists of proteins folded into a specific cross beta-pleated sheet structure. This fibrillar structure has been found as an alternative folding pattern for a variety of functional proteins. Deposits of amyloid in the form of AMYLOID PLAQUES are associated with a variety of degenerative diseases. The amyloid structure has also been found in a number of functional proteins that are unrelated to disease.Alzheimer Disease: A degenerative disease of the BRAIN characterized by the insidious onset of DEMENTIA. Impairment of MEMORY, judgment, attention span, and problem solving skills are followed by severe APRAXIAS and a global loss of cognitive abilities. The condition primarily occurs after age 60, and is marked pathologically by severe cortical atrophy and the triad of SENILE PLAQUES; NEUROFIBRILLARY TANGLES; and NEUROPIL THREADS. (From Adams et al., Principles of Neurology, 6th ed, pp1049-57)Protein PrecursorsPeptide Fragments: Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.Amyloid Precursor Protein Secretases: Endopeptidases that are specific for AMYLOID PROTEIN PRECURSOR. Three secretase subtypes referred to as alpha, beta, and gamma have been identified based upon the region of amyloid protein precursor they cleave.Smilacaceae: A plant family of the order Liliales, subclass Liliidae, class Liliopsida (monocotyledon).Plaque, Amyloid: Accumulations of extracellularly deposited AMYLOID FIBRILS within tissues.Cerebral Amyloid Angiopathy: A heterogeneous group of sporadic or familial disorders characterized by AMYLOID deposits in the walls of small and medium sized blood vessels of CEREBRAL CORTEX and MENINGES. Clinical features include multiple, small lobar CEREBRAL HEMORRHAGE; cerebral ischemia (BRAIN ISCHEMIA); and CEREBRAL INFARCTION. Cerebral amyloid angiopathy is unrelated to generalized AMYLOIDOSIS. Amyloidogenic peptides in this condition are nearly always the same ones found in ALZHEIMER DISEASE. (from Kumar: Robbins and Cotran: Pathologic Basis of Disease, 7th ed., 2005)Aspartic Acid Endopeptidases: A sub-subclass of endopeptidases that depend on an ASPARTIC ACID residue for their activity.Amyloid Neuropathies: Disorders of the peripheral nervous system associated with the deposition of AMYLOID in nerve tissue. Familial, primary (nonfamilial), and secondary forms have been described. Some familial subtypes demonstrate an autosomal dominant pattern of inheritance. Clinical manifestations include sensory loss, mild weakness, autonomic dysfunction, and CARPAL TUNNEL SYNDROME. (Adams et al., Principles of Neurology, 6th ed, p1349)Moraceae: The mulberry plant family of the order Urticales, subclass Hamamelidae, class Magnoliopsida. They have milky latex and small, petalless male or female flowers.Endopeptidases: A subclass of PEPTIDE HYDROLASES that catalyze the internal cleavage of PEPTIDES or PROTEINS.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Iridoid Glycosides: A subclass of iridoid compounds that include a glycoside moiety, usually found at the C-1 position.Molecular Sequence Data: 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.Amino Acid Sequence: 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.Serum Amyloid A Protein: An ACUTE PHASE REACTION protein present in low concentrations in normal sera, but found at higher concentrations in sera of older persons and in patients with AMYLOIDOSIS. It is the circulating precusor of amyloid A protein, which is found deposited in AA type AMYLOID FIBRILS.Neurons: The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.Mice, Transgenic: Laboratory mice that have been produced from a genetically manipulated EGG or EMBRYO, MAMMALIAN.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Cerebral Cortex: The thin layer of GRAY MATTER on the surface of the CEREBRAL HEMISPHERES that develops from the TELENCEPHALON and folds into gyri and sulchi. It reaches its highest development in humans and is responsible for intellectual faculties and higher mental functions.Protein Processing, Post-Translational: Any of various enzymatically catalyzed post-translational modifications of PEPTIDES or PROTEINS in the cell of origin. These modifications include carboxylation; HYDROXYLATION; ACETYLATION; PHOSPHORYLATION; METHYLATION; GLYCOSYLATION; ubiquitination; oxidation; proteolysis; and crosslinking and result in changes in molecular weight and electrophoretic motility.Amyloidosis: A group of sporadic, familial and/or inherited, degenerative, and infectious disease processes, linked by the common theme of abnormal protein folding and deposition of AMYLOID. As the amyloid deposits enlarge they displace normal tissue structures, causing disruption of function. Various signs and symptoms depend on the location and size of the deposits.Disease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.Islet Amyloid Polypeptide: A pancreatic beta-cell hormone that is co-secreted with INSULIN. It displays an anorectic effect on nutrient metabolism by inhibiting gastric acid secretion, gastric emptying and postprandial GLUCAGON secretion. Islet amyloid polypeptide can fold into AMYLOID FIBRILS that have been found as a major constituent of pancreatic AMYLOID DEPOSITS.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Aging: The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.Interleukin-1beta: An interleukin-1 subtype that is synthesized as an inactive membrane-bound pro-protein. Proteolytic processing of the precursor form by CASPASE 1 results in release of the active form of interleukin-1beta from the membrane.RNA, Messenger: RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.Presenilin-1: Integral membrane protein of Golgi and endoplasmic reticulum. Its homodimer is an essential component of the gamma-secretase complex that catalyzes the cleavage of membrane proteins such as NOTCH RECEPTORS and AMYLOID BETA-PEPTIDES precursors. PSEN1 mutations cause early-onset ALZHEIMER DISEASE type 3 that may occur as early as 30 years of age in humans.Serum Amyloid P-Component: Amyloid P component is a small, non-fibrillar glycoprotein found in normal serum and in all amyloid deposits. It has a pentagonal (pentaxin) structure. It is an acute phase protein, modulates immunologic responses, inhibits ELASTASE, and has been suggested as an indicator of LIVER DISEASE.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Congo Red: An acid dye used in testing for hydrochloric acid in gastric contents. It is also used histologically to test for AMYLOIDOSIS.Insulysin: An enzyme the catalyzes the degradation of insulin, glucagon and other polypeptides. It is inhibited by bacitracin, chelating agents EDTA and 1,10-phenanthroline, and by thiol-blocking reagents such as N-ethylmaleimide, but not phosphoramidon. (Eur J Biochem 1994;223:1-5) EC Proteins: Proteins prepared by recombinant DNA technology.Cloning, Molecular: The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.Vitellogenins: Phospholipoglycoproteins produced in the fat body of egg-laying animals such as non-mammalian VERTEBRATES; ARTHROPODS; and others. Vitellogenins are secreted into the HEMOLYMPH, and taken into the OOCYTES by receptor-mediated ENDOCYTOSIS to form the major yolk proteins, VITELLINS. Vitellogenin production is under the regulation of steroid hormones, such as ESTRADIOL and JUVENILE HORMONES in insects.Kinetics: The rate dynamics in chemical or physical systems.S100 Calcium Binding Protein beta Subunit: A calcium-binding protein that is 92 AA long, contains 2 EF-hand domains, and is concentrated mainly in GLIAL CELLS. Elevation of S100B levels in brain tissue correlates with a role in neurological disorders.Vitellogenesis: The active production and accumulation of VITELLINS (egg yolk proteins) in the non-mammalian OOCYTES from circulating precursors, VITELLOGENINS. Vitellogenesis usually begins after the first MEIOSIS and is regulated by estrogenic hormones.Peptides: Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.beta 2-Microglobulin: An 11-kDa protein associated with the outer membrane of many cells including lymphocytes. It is the small subunit of the MHC class I molecule. Association with beta 2-microglobulin is generally required for the transport of class I heavy chains from the endoplasmic reticulum to the cell surface. Beta 2-microglobulin is present in small amounts in serum, csf, and urine of normal people, and to a much greater degree in the urine and plasma of patients with tubular proteinemia, renal failure, or kidney transplants.Transfection: The uptake of naked or purified DNA by CELLS, usually meaning the process as it occurs in eukaryotic cells. It is analogous to bacterial transformation (TRANSFORMATION, BACTERIAL) and both are routinely employed in GENE TRANSFER TECHNIQUES.Presenilin-2: Integral membrane protein of Golgi and endoplasmic reticulum. Its homodimer is an essential component of the gamma-secretase complex that catalyzes the cleavage of membrane proteins such as NOTCH RECEPTORS and AMYLOID BETA-PEPTIDES precursors. PSEN2 mutations cause ALZHEIMER DISEASE type 4.ThiazolesBlotting, Western: Identification of proteins or peptides that have been electrophoretically separated by blot transferring from the electrophoresis gel to strips of nitrocellulose paper, followed by labeling with antibody probes.tau Proteins: Microtubule-associated proteins that are mainly expressed in neurons. Tau proteins constitute several isoforms and play an important role in the assembly of tubulin monomers into microtubules and in maintaining the cytoskeleton and axonal transport. Aggregation of specific sets of tau proteins in filamentous inclusions is the common feature of intraneuronal and glial fibrillar lesions (NEUROFIBRILLARY TANGLES; NEUROPIL THREADS) in numerous neurodegenerative disorders (ALZHEIMER DISEASE; TAUOPATHIES).Neurofibrillary Tangles: Abnormal structures located in various parts of the brain and composed of dense arrays of paired helical filaments (neurofilaments and microtubules). These double helical stacks of transverse subunits are twisted into left-handed ribbon-like filaments that likely incorporate the following proteins: (1) the intermediate filaments: medium- and high-molecular-weight neurofilaments; (2) the microtubule-associated proteins map-2 and tau; (3) actin; and (4) UBIQUITINS. As one of the hallmarks of ALZHEIMER DISEASE, the neurofibrillary tangles eventually occupy the whole of the cytoplasm in certain classes of cell in the neocortex, hippocampus, brain stem, and diencephalon. The number of these tangles, as seen in post mortem histology, correlates with the degree of dementia during life. Some studies suggest that tangle antigens leak into the systemic circulation both in the course of normal aging and in cases of Alzheimer disease.Membrane Proteins: Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.