CLONING AND EXPRESSION OF THE RB-RELATED MOUSE P130 MESSENGER-RNA

The mouse p130 cDNA was cloned from a thymus-derived library using the human p130 cDNA as a probe. The 4515-bp mouse cDNA encodes a putative 1092 aa protein with predicted molecular mass of 123kD. Comparison of mouse and human sequences reveals the mouse protein lacks 43 aa in a conserved domain, relative to the human sequence, located amino-termin al to the pocket region. Northern analysis of P19 embryonal carcinoma (EC) and RA-induced P19 cultures indicates p130 mRNA is not expressed at detectable levels in undifferentiated stem cells and is strongly up regulated after post-mitotic neurons begin to accumulate. Northern ana lysis of adult mouse tissues indicated that the 4.8 kb p130 mRNA is ex pressed ubiquitously, however, a putative 9-truncated 1.7 kb isoform i s detected solely in testis. Forced expression of mouse p130 induced g rowth suppression of P19 EC cells and Western analysis of transfected P19 cells suggested the cloned cDNA encodes the full-length p130 prote in.