Seven In Absentia Homolog 2 (SIAH2)

SIAH2 encodes a protein that is a member of the seven in absentia homolog (SIAH) family. The protein is an E3 ligase and is involved in ubiquitination and proteasome-mediated degradation of specific proteins. SIAH1 and SIAH2 are expressed in many normal and neoplastic tissues, and only subtle differences in their expression were noted. However, 1 of 3 murine homologs, Siah1b, was strongly induced in fibroblasts undergoing apoptotic cell death. While a previous study suggested that sina is a nuclear protein, epitope-labeled sina and SIAH1 proteins were found in the cytoplasm of Drosophila and mammalian cells. Their substantial evolutionary conservation, role in specifying cell fate, and activation in apoptotic cells suggested that the SIAH proteins have important roles in vertebrate development.