PAX Interacting Protein 1 (PAXIP1)

PAXIP1 is a member of the paired box (PAX) gene family and encodes a nuclear protein with six BRCT (breast cancer carboxy-terminal) domains. This protein plays a critical role in maintaining genome stability, condensation of chromatin and progression through mitosis.

The deduced 1,056-amino acid protein has a calculated molecular mass of 119.3 kD. Ptip contains 2 N-terminal and 3 C-terminal BRCA1 (BRCT) domains separated by a glutamine-rich region. Northern blot analysis of mouse tissues detected ubiquitous expression of a 4.0-kb transcript, with highest expression in embryonic kidney and brain. PTIP was also expressed in all human and mouse cell lines examined. In mouse fibroblasts, Ptip localized to the nucleus.