Calcyclin Binding Protein (CACYBP)

Calcyclin-binding protein is a calcyclin binding protein. It may be involved in calcium-dependent ubiquitination and subsequent proteosomal degradation of target proteins. It probably serves as a molecular bridge in ubiquitin E3 complexes and participates in the ubiquitin-mediated degradation of beta-catenin. The full-length SIP cDNA encodes a predicted 228-amino acid protein. Sequence analysis of the shortest cDNA derived by 2-hybrid screening revealed an 8-amino acid difference in the deduced open reading frame followed by a stop codon, resulting in a predicted 80-amino acid protein, SIP-short (SIPS). SIPS arises by alternative splicing. The full-length human SIP protein shares 93% amino acid identity with the mouse Sip protein, 40% identity with a counterpart in Drosophila, and 20% identity with the human SGT1 protein.