InterPro domain: IPR037893

This CS p23-like domain is found in the CacyBP/SIP protein (S100A6 binding protein and Siah-1 interacting protein) [ 1 ]. CacyBP/SIP interacts with S100A6 (calcyclin), with some other members of the S100 family, with tubulin, and with Siah-1 and Skp-1 [ 2 ]. The latter two are components of the ubiquitin ligase that regulates beta-catenin degradation. The beta-catenin gene is an oncogene participating in tumorigenesis in many different cancers. Overexpression of CacyBP/SIP, in part through its effect on the expression of beta-catenin, inhibits the proliferation, tumorigenicity, and invasion of gastric cancer cells [ 3 ]. CacyBP/SIP is abundant in neurons and neuroblastoma NB2a cells. An extensive re-organization of microtubules accompanies the differentiation of NB2a cells. CacyBP/SIP may contribute to NB2a cell differentiation through binding to and increasing the oligomerization of tubulin. CacyBP/SIP is also implicated in differentiation of erythroid cells, rat neonatal cardiomyocytes, in mouse endometrial events, and in thymocyte development [ 4 ].

1. The modular structure of SIP facilitates its role in stabilizing multiprotein assemblies. Biochemistry 44, 9462-71
2. CacyBP/SIP interacts with tubulin in neuroblastoma NB2a cells and induces formation of globular tubulin assemblies. Biochim. Biophys. Acta 1773, 1628-36
3. S100A6 binding protein and Siah-1 interacting protein (CacyBP/SIP): spotlight on properties and cellular function. Amino Acids 41, 773-80
4. Calcyclin-binding protein inhibits proliferation, tumorigenicity, and invasion of gastric cancer. Mol. Cancer Res. 5, 1254-62