The calcium-binding Protein S100A2 is a member of the S100 family of proteins containing 2 EF-hand calcium-binding motifs. S100 family genes are located as a cluster on chromosome 1q21; and S100 proteins consisting of at least 20 members are involved in the regulation of a number of cellular processes such as cell-cycle progression and cell differentiation. S100A2 was first detected in lung and kidney; and is mainly expressed in a subset of tissues and cells such as breast epithelia and liver. The S100A2 protein is a homodimer that undergoes a conformational change upon binding of calcium; and the active form functions in regulating cell proliferation and differentiation; gene transcription; and p53-dependent growth arrest and apoptosis. Accordingly; this protein is regarded as a putative tumor suppressor; and thus chromosomal rearrangements and reduced expression of S100A2 gene have been implicated in certain carcinomas.
Protein S100-A3, also known as Protein S-100E, S100 calcium-binding protein A3, S100A3 and S100E, is a member of the S-100 family. S100A3 / S100E contains 2EF-hand domains. S100A3 / S100E is highly expressed in the differentiating cuticular cells within the hair follicle and organized into mature hair cuticles. High concentrations of S100A3 homotetramer might provide the millimolar level of Ca2+ required for hair cuticular barrier formation. S100A3 / S100E is a unique member of the Ca2+-binding S100 protein family with the highest cysteine content and affinity for Zn2+. S100A3 / S100E binds both calcium and zinc. S100A3 / S100E probably binds 2 zinc ions per molecule. It may be involved in calcium-dependent cuticle cell differentiation and hair shaft formation. S100A3 plays an important role in calcium-dependent processes leading to hair shaft formation. S100A3 / S100E is a unique protein among all members of the calcium-binding S100 family, is specifically expressed at the inner endocuticle of human hair fibers. Upon hair damage, S100A3 / S100E is released from hair fibers and possibly destabilizes the hair tissue architecture.
S100A4, also known as metastasis-associated protein Mtsl, belongs to the family of small calcium-binding S100 proteins containing two EF-hand calcium-binding motifs. In humans at least 20 S100 family members that are distributed tissue specifically have been identified, and are involved in a number of cellular processes as transducers of calcium signal. S100A4 is a symmetric homodimer, and undergoes a relatively large conformational change upon the typical EF-hand binding calcium, which is necessary for S100A4 to interact with its protein targets and generate biological effects. It can bind the already known targets p53, F-actin, liprin β, myosin heavy chain II, and prevent their phosphorylation and multimerization. It has been demonstrated that S100A4 is directly involved in tumor metastasis including cell motility, invasion, apoptosis, angiogenesis and differentiation, and appears to be a metastasis factor and a molecular marker for clinical prognosis. Multiple alternatively spliced variants encoding the same protein have been identified.
S100A4 is a member of the S100 family of proteins. The S100 family is further classified as a member of the EF-hand superfamily of Ca++-binding proteins. These participate in both calcium-dependent and calcium-independent protein-protein interactions. The hallmark of this superfamily is the EF-hand motif that consists of a Ca++-binding site flanked by two α-helices (helix E and helix F) that were originally identified in a right-handed model of carp muscle calcium-binding protein. Human S100A4 is 101 amino acids (aa) in length. It contains two EF hand domains, one between aa 12-47, and a second between aa 50-85. S100A4 activity has been associated with cell transformation. It seems likely this is either coincidental, or a consequence, rather than a cause of transformation.
S100 protein is a family of low molecular weight protein found in vertebrates characterized by two EF-hand calcium-binding motifs. There are at least 21 different S100 proteins, and the name is derived from the fact that the protein is 100% soluble in ammonium sulfate at neutral pH. Most S100 proteins are disulfide-linked homodimer, and is normally present in cells derived from the neural crest, chondrocytes, macrophages, dendritic cells, etc. S100 proteins have been implicated in a variety of intracellular and extracellular functions. They are involved in regulation of protein phosphorylation, transcription factors, the dynamics of cytoskeleton constituents, enzyme activities, cell growth and differentiation, and the inflammatory response. Protein S100-A5, also known as Protein S-100D, S100 calcium-binding protein A5, S100A5 and S100D, is a member of the S100 family which contains two EF-hand domains. S100A5 is also a novel member of the EF-hand superfamily of calcium-binding proteins that is poorly characterized at the protein level. It is expressed in very restricted regions of the adult brain. From birth onwards, S100A5 remained a neuronal-specific protein, only located in a subpopulation of neurons in the spiral ganglion.
S100 proteinis a family of low molecular weight protein found in vertebrates characterized by twoEF-hand calcium-binding motifs. There are at least 21 different S100 proteins; and the name is derived from the fact that the protein is100%soluble in ammonium sulfateat neutralpH. Most S100 proteins are disulfide-linked homodimer; and is normally present in cells derived from theneural crest; chondrocytes; macrophages; dendritic cells; etc. S100 proteins have been implicated in a variety of intracellular and extracellular functions. They are involved in regulation of protein phosphorylation; transcription factors; the dynamics of cytoskeleton constituents; enzyme activities; cell growth and differentiation; and the inflammatory response. S100A6 (S100 calcium binding protein A6) is a member of the S100 family of proteins; and functions in prolactin secretion; and exocytosis. Chromosomal rearrangements and altered expression of S100A6 have been implicated in melanoma.
S100A6, also known as Protein S100-A6, Calcyclin, Growth factor-inducible protein 2A9, MLN 4, Prolactin receptor-associated protein, PRA, S100 calcium-binding protein A6 and CACY, is a member of the S100 family of proteins containing 2 EF-hand calcium-binding motifs.S100 proteins are a family of low molecular weight protein found in vertebrates and localized in the cytoplasm and/or nucleus of a wide range of cells.S100 proteins are involved in a number of fundamental biological processes such as protein phosphorylation, transcription factors, the dynamics of cytoskeleton constituents, enzyme activities, cell growth and differentiation, the inflammatory response,cell cycle progression and differentiation, stimulation of Ca2+-dependent insulin release, stimulation of prolactin secretion, and exocytosis. Chromosomal rearrangements and altered expression of this gene have been implicated in melanoma. S100A6 may function as calcium sensor and modulator, contributing to cellular calcium signaling.It may function by interacting with other proteins, such as TPR-containing proteins, and indirectly play a role in many physiological processes such as the reorganization of the actin cytoskeleton and in cell motility.
S100A7 is a 11-12 kDa member of the S100 family of EF hand calcium binding proteins. Human S100A7 shares 32% amino acid sequence identity with mouse S100A7A, the closest related protein in mouse. It is acetylated at the N-terminus and binds both calcium and zinc ions. S100A7 is up-regulated in keratinocytes of psoriasis and atopic dermatitis lesions, as well as in epithelial cells of the tongue, eye, and female genital tract. Its up-regulation can be induced by bacterial exposure, inflammatory cytokines, or epidermal barrier disruption. S100A7 supports epithelial integrity through killing E. coli by sequestration of zinc and through inducing the up-regulation of tight junction proteins. The interaction of S100A7 with RAGE promotes the migration of immune cells and the infiltration of macrophages into tumor sites.
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