Isolation and chromosomal localization of a new human retinoblastoma binding protein 2 homologue 1a (RBBP2H1A)

Using a Nod linking clone NR-025 as a probe, we isolated a novel putative m ember of the RE binding protein family, namely a human retinoblastoma bindi ng protein 2 homologue (RBBP2H1A). The maximal open reading frame encodes a protein of 1681 amino acids. Homology analysis indicated that the predicte d product has an overall 56% amino acid identity to RBBP2, which plays an i mportant role in RE tumor suppressor regulation. Many extended regions are 100% identical in amino acids sequences. The degree of nucleotide identity is lower. The structure prediction analysis identified three DNA-binding zi nc finger domains and two bipartite nuclear localization signals. Northern expression analysis revealed expression in all tissues; however, the level of expression significantly varied between tissues. The highest level of ex pression was detected in testis and the lowest in skeletal muscle. The mRNA sizes corresponding to two major products are around 6kb and 7kb, Using fl uorescence in situ hybridization, we mapped the gene to chromosomal band 1q 32.1.