The retinoblastoma protein binds to RIZ, a zinc-finger protein that shares an epitope with the adenovirus E1A protein.
The retinoblastoma protein (Rb) is a target of viral oncoproteins. To explore the hypothesis that viral proteins may be structural mimics of cellular proteins, we have searched cDNA libraries for Rb-binding proteins. We report here the cloning of a cDNA for the protein RIZ from rat and human cells. RIZ is a 250-kDa nuclear protein containing eight zinc-finger motifs. It contains an Rb-binding motif that shares an antigenic epitope with the C terminus of E1A. A domain is conserved between RIZ and the PRDI-BF1/Blimp-1 differentiation factor. Other motifs of RIZ include putative GTPase and SH3 (src homology domain 3) domains. RIZ is preferentially expressed in both adult and embryonic rat neuroendocrine tissues. It is also expressed in human retinoblastoma cells and at low levels in all other human cell lines examined. While the function of RIZ is not yet clear, its structure and pattern of expression suggest a role for RIZ in transcriptional regulation during neuronal differentiation and pathogenesis of retinoblastoma.
Buyse
I M
IM
Cancer Research Center, La Jolla Cancer Research Foundation, CA 92037, USA.
Shao
G
G
Huang
S
S
D017500:Adenovirus E1A Proteins / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D003001:Cloning, Molecular; D016384:Consensus Sequence; D004268:DNA-Binding Proteins; D004622:Embryo, Mammalian; D000939:Epitopes / Q000032:analysis*; D020558:GTP Phosphohydrolases / Q000276:immunology / Q000378:metabolism; D015723:Gene Library; D011495:Histone-Lysine N-Methyltransferase; D006801:Humans; D015151:Immunoblotting; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism; D009687:Nuclear Proteins / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism*; D009928:Organ Specificity; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors; D014407:Tumor Cells, Cultured; D016335:Zinc Fingers
D017500:Adenovirus E1A Proteins; D004268:DNA-Binding Proteins; D000939:Epitopes; D009687:Nuclear Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D016160:Retinoblastoma Protein; D014157:Transcription Factors; D011495:Histone-Lysine N-Methyltransferase; C093563:PRDM2 protein, human; D020558:GTP Phosphohydrolases