RAD9 Homolog B (RAD9B)

RAD9B associated with 3 endogenous checkpoint proteins, HUS1, RAD1, and RAD17, possibly in a 9-1-1-like complex. RAD9B also interacted with transfected HUS1B. The deduced 414-amino acid protein shares 36% overall sequence identity with RAD9A, with highest homology in their N-terminal PCNA-like regions, and contains only 2 of the 10 C-terminal phosphorylation sites found in RAD9A. Dufault et al. (2003) also cloned mouse Rad9b, which shares high homology in the PCNA-like region with human RAD9A and RAD9B. Northern blot analysis of several human tissues detected transcripts of 4.4, 3.0, and 2.2 kb at high levels in testis and lower levels in skeletal muscle. Little to no expression was detected in other tissues.