Calcium Binding Protein P22 (CHP1) Human Recombinant Protein

This gene encodes a phosphoprotein that binds to the Na+/H+ exchanger NHE1. This protein serves as an essential cofactor which supports the physiological activity of NHE family members and may play a role in the mitogenic regulation of NHE1. The protein shares similarity with calcineurin B and calmodulin and it is also known to be an endogenous inhibitor of calcineurin activity. [provided by RefSeq, Jul 2008]

CHP: Calcium-binding protein involved in different processes such as regulation of vesicular trafficking, plasma membrane Na(+)/H(+) exchanger and gene transcription. Involved in the constitutive exocytic membrane traffic. Mediates the association between microtubules and membrane-bound organelles of the endoplasmic reticulum and Golgi apparatus and is also required for the targeting and fusion of transcytotic vesicles (TCV) with the plasma membrane. Functions as an integral cofactor in cell pH regulation by controlling plasma membrane-type Na(+)/H(+) exchange activity. Affects the pH sensitivity of SLC9A1/NHE1 by increasing its sensitivity at acidic pH. Required for the stabilization and localization of SLC9A1/NHE1 at the plasma membrane. Inhibits serum- and GTPase-stimulated Na(+)/H(+) exchange. Plays a role as an inhibitor of ribosomal RNA transcription by repressing the nucleolar UBF1 transcriptional activity. May sequester UBF1 in the nucleoplasm and limit its translocation to the nucleolus. Associates to the ribosomal gene promoter. Acts as a negative regulator of the calcineurin/NFAT signaling pathway. Inhibits NFAT nuclear translocation and transcriptional activity by suppressing the calcium-dependent calcineurin phosphatase activity. Also negatively regulates the kinase activity of the apoptosis-induced kinase STK17B. Inhibits both STK17B auto- and substrate- phosphorylations in a calcium-dependent manner. Belongs to the calcineurin regulatory subunit family. CHP subfamily.

Protein type: Calcium-binding

Chromosomal Location of Human Ortholog: 15q13.3

Cellular Component: microtubule cytoskeleton; Golgi membrane; transport vesicle; focal adhesion; endoplasmic reticulum; cytoplasm; ER-Golgi intermediate compartment; plasma membrane; nucleus; cytosol

Molecular Function: protein binding; potassium channel regulator activity; protein kinase inhibitor activity; transporter activity; microtubule binding; calcium ion binding; kinase binding; calcium-dependent protein binding

Biological Process: glycosaminoglycan metabolic process; pathogenesis; negative regulation of protein import into nucleus; cytoplasmic microtubule organization and biogenesis; hyaluronan catabolic process; negative regulation of protein amino acid phosphorylation; positive regulation of protein amino acid glycosylation; small GTPase mediated signal transduction; negative regulation of protein amino acid autophosphorylation; protein export from nucleus; membrane docking; potassium ion transport; protein stabilization; transcytosis; protein oligomerization; calcium ion-dependent exocytosis; positive regulation of protein transport; inhibition of NF-kappaB transcription factor; regulation of intracellular pH; carbohydrate metabolic process; negative regulation of protein kinase activity; negative regulation of protein ubiquitination; positive regulation of sodium:hydrogen antiporter activity; hyaluronan metabolic process; microtubule bundle formation