S100A10

1A4P, 1BT6, 4DRW, 4FTG, 4HRE, 4HRG, 4HRH628120194ENSG00000197747ENSMUSG00000041959P60903P08207NM_002966NM_009112NP_002957NP_033138S100 calcium-binding protein A10 (S100A10), also known as p11, is a protein that is encoded by the S100A10 gene in humans and the S100a10 gene in other species. S100A10 is a member of the S100 family of proteins containing two EF-hand calcium-binding motifs. S100 proteins are localized in the cytoplasm and/or nucleus of a wide range of cells. They regulate a number of cellular processes such as cell cycle progression and differentiation. The S100 protein is implicated in exocytosis and endocytosis by reorganization of F-actin.1a4p: P11 (S100A10), LIGAND OF ANNEXIN II1bt6: P11 (S100A10), LIGAND OF ANNEXIN II IN COMPLEX WITH ANNEXIN II N-TERMINUS S100 calcium-binding protein A10 (S100A10), also known as p11, is a protein that is encoded by the S100A10 gene in humans and the S100a10 gene in other species. S100A10 is a member of the S100 family of proteins containing two EF-hand calcium-binding motifs. S100 proteins are localized in the cytoplasm and/or nucleus of a wide range of cells. They regulate a number of cellular processes such as cell cycle progression and differentiation. The S100 protein is implicated in exocytosis and endocytosis by reorganization of F-actin. The p11 protein is linked with the transport of neurotransmitters. Found in the brain of humans and other mammals, it has been implicated in the regulation of mood. In addition, due to its interaction with serotonin-signaling proteins and its correlation with symptoms of mood disorders, p11 is a new potential target for drug therapy. The S100 gene family includes at least 13 members that are located as a cluster on chromosome 1q21. In humans, 19 family members arecurrently known, with most S100 genes (S100A1 to S100A16). The p11 protein can be found as a free monomer, a homodimer, or a heterotetramer composed of a p11 dimer complex with two molecules of annexin II. The homodimer or heterotetramer can, in turn, dimerize through formation of two disulfide bonds (see figure to the left). The p11 monomer is an asymmetric protein composed of four alpha helices. The dimerized form of the protein is created by packing between the H1 and H4 helices in an antiparallel arrangement with the hydrophobic regions residing in the core. The structure of p11 is classified by a pair of the helix-loop-helix motif, also known as the EF-hand-type that recognizes and binds calcium ions. This is common to all known S-100 proteins. The EF-hand types, united by an anti-parallel beta-strand between loops L1 and L3, are located on the same side of the molecule, opposite the N-and C-termini. As a member of the S-100 family, its structure resembles that of the S-100A1 and S-100B proteins. This class of proteins has been implicated in the regulation of cytoskeleton assembly, cytosolic enzymes, and membrane dynamics. P11's involvement with the cytoskeleton may aid the transport of other proteins throughout the cell and to the cell membrane. Unlike other S-100 proteins, the second EF-hand of protein p11 is incapable of binding calcium due to a series of mutations caused by deletions and substitutions. Annexin II, which is attracted to negatively charged phospholipids, binds to p11 at the Ca2+ binding site. In addition, Annexin II has been implicated in membrane-cytoskeleton interactions and in regulations of ion currents and substances across the membrane. P11 and annexin II form a heterotetrameric protein complex that imitates the structure and function of S-100 proteins activated by the binding of calcium. This tetrameric complex is more stable than the p11 dimer, therefore the overexpression of the annexin II gene results in higher levels of p11 protein. P11 is an integral part of cellular structural scaffolding that interacts with plasma membrane proteins through its association with annexin II. Recently, it was discovered to form a complex with annexin I though the mechanism remains unknown. It works together with cytosolic and peripheral membrane-associated proteins such as AHNAK in the development of the intracellular membrane. P11 has been implicated in the transportation of proteins involved in mood regulation, nociception, and cell polarization. It is found in cell types throughout the body though it is located predominantly in the lungs and kidneys. It is involved in the trafficking of proteins to the plasma membrane and can be expressed on the cell surface as a receptor. Many of the transported proteins are cell surface receptors in signal transduction pathways and ion channels. P11 facilitates nociception, Ca2+ uptake, and cell polarization. Complexed with the annexin II, p11 binds receptor and channel proteins and guides them to the cell surface, resulting in increased membrane localization and consequent magnified functional expression of these proteins. Ion channels are among the several proteins that are transported through the interaction with p11. Some of these proteins include Nav1.8, TRPV5, TRPV6, TASK-1, and ASIC1a. Nav1.8 is a tetrodotoxin-resistant sodium channel that replaces lost sodium after cell damage. Increased expression of these channels alters the magnitude of the sodium current across the membrane. TRPV5 and TRPV6 are transient receptor potential channels selective for Ca+ and Mg2+ ions. TASK-1 is a two-pore domain K+ channel TWIK-related acid-sensitive K (TASK). P11 can also function as a retention factor, preventing TASK-1 from leaving the endoplasmic reticulum. ASIC1a is an acid-sensing ion channel involved in the pain sensory pathway, which is regulated by p11. Although the exact mechanism is unclear, p11 protein has shown to be essential in the regulation of serotonin signaling in the brain. Serotonin (5-hydroxytryptamine or 5-HT), is a neurotransmitter found in the central and peripheral nervous systems. It is involved in mechanisms responsible for memory formation and learning, but is most known for its role in the regulation muscle contraction, appetite, sleep, and mood. Varying levels of serotonin found in the brain are associated with the development of mood disorders, such as clinical depression. P11 interacts with the serotonin receptor proteins, 5-HT receptors such as 5-HT1B, modulating the receptor signal transduction pathways activated by the binding of serotonin. P11 also recruits the cell surface expression of the 5-HT4 receptor, increasing its concentration at the synapse. This results in more rapid serotonin-dependent activities. 5-HT4 is involved in the regulation of kinase activity in the central nervous system, phosphorylating target proteins, and facilitating endosomal activities. P11 is coexpressed with 5-HT4 mRNA and its protein in parts of the brain associated with depression, suggesting that their functions are linked and influence mood.