A conserved family of WD-40 proteins binds to the retinoblastoma protein in both plants and animals.
In mammalian cells, the retinoblastoma (RB) protein regulates G1 progression and functions through its association with various cellular proteins. Two closely related mammalian RB binding proteins, RbAp48 and RbAp46, share sequence homology with the Msi1 protein of yeast. MSI1 is a multicopy suppressor of a mutation in the IRA1 gene involved in the Ras-cAMP pathway that regulates cellular growth. Human RbAp48 is present in protein complexes involved in histone acetylation and chromatin assembly. We report the cloning of cDNAs encoding four plant RbAp48- and Msi1-like proteins: one from tomato, LeMSI1, and three from Arabidopsis. Complementation studies confirm that LeMSI1 can function as a multicopy suppressor of the yeast ira1 mutant phenotype. The LeMSI1 protein localizes to the nucleus and binds to a 65-kD protein in wild-type as well as ripening inhibitor (rin) and Neverripe (Nr) tomato fruit. LeMSI1 also binds to the human RB protein and the RB-like RRB1 protein from maize, indicating that this interaction is conserved between plants and animals.
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Department of Plant and Microbial Biology, University of California, Berkeley 94720-3102, USA.
Taranto
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Gruissem
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D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics*; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D017124:Conserved Sequence; D006801:Humans; D018551:Solanum lycopersicum / Q000166:cytology / Q000235:genetics*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D010641:Phenotype; D010940:Plant Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D016160:Retinoblastoma Protein / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D003313:Zea mays / Q000378:metabolism
D002352:Carrier Proteins; C108988:MSI1 protein, Lycopersicon esculentum; D009687:Nuclear Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; D016160:Retinoblastoma Protein