MOLECULAR-CLONING, EXPRESSION, AND DEVELOPMENTAL CHARACTERIZATION OF THE MURINE RETINOBLASTOMA-RELATED GENE RB2 P130/

The product of the retinoblastoma-related human gene Rb2/p130 is highl y homologous with the product of the retinoblastoma tumor suppressor g ene (pRb) and Rb-related p107. This homology is shared mainly in the p ocket domain, a region that seems to play a key role in the functions of these proteins. Here we report the molecular cloning and initial ch aracterization of the cDNA encoding the murine homologue of the human Rb2/p130 gene product. The 4.8-kb cDNA encodes a protein of 1125 amino acids that shows 90% identity to that of the human protein. The Rb2/p 130 mRNA is found to be expressed in all of the adult mouse tissues ex amined, with the highest revel being detected in kidney and skeletal m uscle. For the protein characterization, we used a polyclonal antibody raised against the COOH terminus of the human Rb1/p130 protein that a lso recognizes the mouse protein. In developing mouse embryos, the Rb2 /p130 protein is expressed as early as day 10 of gestation and reached a peak of expression around day 13 of gestation, implying a developme ntal regulation of the R62/p130 gene in murine ontogeny.