Description
RBL1 (Retinoblastoma-like 1), also known as Cullular Proteins p107, and CP107, is a protein that in humans is encoded by the RBL1 gene. Ewen et al.(1991) used a partial cDNA for human p107 to map the gene to 20q11. by fluorescence in situ hybridization. Huppi et al.(1996)found that the mouse Rbl1 gene maps to the distal end of chromosome 2, as does also the E2f1 gene. The protein encoded by this gene is similar in sequence and possibly function to the product of the retinoblastoma 1 (RB1) gene. The RB1 gene product is a tumor suppressor protein that appears to be involved in cell cycle regulation, as it is phosphorylated in the S to M phase transition and is dephosphorylated in the G1 phase of the cell cycle. Both the RB1 protein and the product of this gene can form a complex with adenovirus E1A protein and SV40 Large T-antigen, with the SV40 large T-antigen binding only to the unphosphorylated form of each protein. In addition, both proteins can inhibit the transcription of cell cycle genes containing E2F binding sites in their promoters. Due to the sequence and biochemical similarities with the RB1 protein, it is though that the protein encoded by this gene may also be a tumor suppressor. Two transcript variants encoding different isoforms have been found for this gene