ISOLATION AND SEQUENCE POLYMORPHISM OF A RAT RETINOBLASTOMA (RB) CDNA

A cDNA of the rat retinoblastoma gene (RB) was prepared from total RNA of rat liver using reverse transcription-polymerase chain reaction (R T-PCR). The 4432-nt sequence isolated contained 2700-nt translated and 1732-nt 3'-untranslated regions (UTR). The isolated cDNA detected pol y(A)(+)RNAs of 5.4 and 3.4 kb in rat liver and kidney by Northern blot hybridization. The nt sequence of the isolated cDNA had 85% homology with that of mouse and 73% with human. The 899-amino-acid (aa) sequenc e was 95% homologous to that of mouse and 90% to human. The aa sequenc es of two functional domains of oncoprotein-binding and ten putative p hosphorylation sites regulating RB function were conserved in the thre e species, However, the 3'-UTR were less homologous among the three, a nd had polymorphism in three portions, even in rats. These polymorphis ms were strain-specific and genetically segregated. Thus, the rat RE c DNA and its sequence information may be useful for clarifying the role of the RB protein and genetic linkage analysis in basic biomedical re search using rats, especially in experimental carcinogenesis.