ISOLATION OF THE RB-RELATED P130 THROUGH ITS INTERACTION WITH CDK2 AND CYCLINS

A two-hybrid protein interaction screen was used to isolate cDNAs enco ding human proteins that can interact with human CDK2 in yeast. A new member of the retinoblastoma susceptibility gene family, Rbr-2 (Rb-rel ated), was obtained. The sequence of the Rbr-2 protein shares approxim ately 50% identity with p107 and homology to Rb within the pocket doma in. Several lines of evidence indicate that Rbr-2 is the adenovirus E1 A-associated p130. Like Rb and p107, p130Rbr-2 can bind to viral oncop roteins, SV40 large T antigen, and adenovirus E1A through its pocket d omain. Although p130Rbr-2 does not bind to CDK2 in vitro, it can inter act with cyclins, with a clear preference for D-type cyclins. Because both CDK2 and p130Rbr-2 show affinity for cyclins, we suggest that p13 0Rbr-2 and CDK2 interacted through a yeast-derived cyclin bridge in th e two-hybrid screen. The gene encoding p130Rbr-2 mapped to 16q13, a re gion of frequent genomic alteration in human tumors.