Anti-SIAH Interacting Protein/CACYBP Antibody Picoband®

CACYBP (Calcyclin-binding protein), also called SIP, is a protein that in humans is encoded by the CACYBP gene. 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) . The CACYBP gene is mapped on 1q25.1. 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. Two alternatively spliced transcript variants encoding different isoforms have been found for this gene. The C-terminal region of SIP that is homologous to SGT1 was able to complement defects in yeast strains containing SGT1 mutant alleles, demonstrating conservation of SGT1 and SIP protein function.

In lung, HT-29 colonic epithelial cells, Raji B-lymphoblasts. Lesser extent in brain, heart, kidney, liver and placenta. Not expressed in CD4+ or CD8+ T-cells. Expressed in the T-cell lines HARRIS, HuT 78, Jurkat and SUP-T1, but not in the T- cell lines Peer, MOLT-4, HSB and YT. .

May be involved in calcium-dependent ubiquitination and subsequent proteasomal degradation of target proteins. Probably serves as a molecular bridge in ubiquitin E3 complexes. Participates in the ubiquitin-mediated degradation of beta-catenin (CTNNB1) . .

1. Matsuzawa, S., Reed, J. C. Siah-1, SIP, and Ebi collaborate in a novel pathway for beta-catenin degradation linked to p53 responses.Molec. Cell 7: 915-926, 2001. 2. Sun S, Ning X, Liu J, et al. (2007) . Overexpressed CacyBP/SIP leads to the suppression of growth in renal cell carcinoma.. Biochem. Biophys. Res. Commun. 356 (4) : 864–71.

Store at -20°C for one year from date of receipt. After reconstitution, at 4°C for one month. It can also be aliquotted and stored frozen at -20°C for six months. Avoid repeated freeze-thaw cycles.

Nucleus . Cytoplasm . Cytoplasmic at low calcium concentrations. In neuroblastoma cells, after a retinoic acid (RA) induction and calcium increase, it localizes in both the nucleus and cytoplasm. The nuclear fraction may be phosphorylated.