CHP1
Description
The CHP1 (calcineurin like EF-hand protein 1) is a protein-coding gene located on chromosome 15.
CHP1 is a calcium-binding protein that plays a role in various cellular processes. It is involved in the regulation of vesicular trafficking, plasma membrane Na(+)/H(+) exchange, and gene transcription. CHP1 also functions as an integral cofactor in cell pH regulation and acts as a negative regulator of the calcineurin/NFAT signaling pathway.
CHP1, also known as calcineurin B-like protein, is a calcium-binding protein involved in various cellular processes, including regulation of vesicle trafficking, plasma membrane Na(+)/H(+) exchange, and gene transcription. It plays a crucial role in constitutive exocytic membrane traffic, mediating the association between microtubules and membrane-bound organelles of the endoplasmic reticulum and Golgi apparatus. Additionally, CHP1 is required for the targeting and fusion of transcytotic vesicles (TCV) with the plasma membrane. As an integral cofactor in cell pH regulation, it controls plasma membrane-type Na(+)/H(+) exchange activity, affecting the pH sensitivity of SLC9A1/NHE1 by increasing its sensitivity at acidic pH. This protein is essential for the stabilization and localization of SLC9A1/NHE1 at the plasma membrane, inhibiting serum- and GTPase-stimulated Na(+)/H(+) exchange. CHP1 also acts as an inhibitor of ribosomal RNA transcription by repressing the nucleolar UBF1 transcriptional activity, possibly sequestering UBF1 in the nucleoplasm and limiting its translocation to the nucleolus. It associates with the ribosomal gene promoter. Furthermore, CHP1 acts as a negative regulator of the calcineurin/NFAT signaling pathway, inhibiting NFAT nuclear translocation and transcriptional activity by suppressing the calcium-dependent calcineurin phosphatase activity. It also negatively regulates the kinase activity of the apoptosis-induced kinase STK17B, inhibiting both STK17B auto- and substrate-phosphorylations in a calcium-dependent manner.
CHP1 is also known as CHP, SLC9A1BP, SPAX9, Sid470p, p22, p24.
