Identification and characterization of RAD9B, a paralog of the RAD9 checkpoint gene.

RAD9 is an integral element of the PCNA-like HUS1-RAD1-RAD9 (9-1-1) complex that participates in genotoxin-induced CHK1 activation. We have identified a novel RAD9 paralog, dubbed RAD9B, in humans and mice. RAD9 and RAD9B share extensive amino acid homology throughout their entire sequences (36% identity, 48% similarity).