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 (RT-PCR). The 4432-nt sequence isolated contained 2700-nt translated and 1732-nt 3'-untranslated regions (UTR). The isolated cDNA detected poly(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) sequence was 95% homologous to that of mouse and 90% to human. The aa sequences of two functional domains of oncoprotein-binding and ten putative phosphorylation sites regulating RB function were conserved in the three species. However, the 3'-UTR were less homologous among the three, and had polymorphism in three portions, even in rats. These polymorphisms were strain-specific and genetically segregated. Thus, the rat RB cDNA and its sequence information may be useful for clarifying the role of the RB protein and genetic linkage analysis in basic biomedical research using rats, especially in experimental carcinogenesis.