p107 and p130: Versatile proteins with interesting pockets

p107 and p130 were originally identified as targets of the transforming dom ains of viral oncoproteins encoded by small DNA tumor viruses. Together wit h pRB, the protein product of the retinoblastoma gene (Rb), p107 and p130 r epresent a family of closely related proteins that play critical roles in t he regulation of cell proliferation. p107, p130, and PRE are transcriptiona l regulators whose activities are coupled to the cell cycle. Each of these proteins associates with E2F and is directly regulated by phosphorylation b y cyclin dependent kinases. In vivo studies of p107 and p130 function have revealed that their roles overlap extensively with one another and with pRB In addition, the analysis of mice (and cell lines derived from these anima ls) deficient in these proteins shows that the individual members of this f amily harbor distinct functions that, at present, are poorly understood. Th e characterization of tumor cells continues to emphasize the important and somewhat unique role of PRE in tumor suppression, and the evidence linking the specific inactivation of p107 or p130 to tumor development remains quit e limited. In this review we summarize the biochemical and functional prope rties of p107 and p130, and we compare and contrast these properties to tho se of pRB. (C) 2001 Academic Press.