Vaults and telomerase share a common subunit, TEP1.
Vaults are large cytoplasmic ribonucleoprotein complexes of undetermined function. Mammalian vaults have two high molecular mass proteins of 193 and 240 kDa. We have identified a partial cDNA encoding the 240-kDa vault protein and determined it is identical to the mammalian telomerase-associated component, TEP1. TEP1 is the mammalian homolog of the Tetrahymena p80 telomerase protein and has been shown to interact specifically with mammalian telomerase RNA and the catalytic protein subunit hTERT. We show that while TEP1 is a component of the vault particle, vaults have no detectable telomerase activity. Using a yeast three-hybrid assay we demonstrate that several of the human vRNAs interact in a sequence-specific manner with TEP1. The presence of 16 WD40 repeats in the carboxyl terminus of the TEP1 protein is a convenient number for this protein to serve a structural or organizing role in the vault, a particle with eight-fold symmetry. The sharing of the TEP1 protein between vaults and telomerase suggests that TEP1 may play a common role in some aspect of ribonucleoprotein structure, function, or assembly.
Kickhoefer
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Department of Biological Chemistry, UCLA School of Medicine and Jonsson Comprehensive Cancer Center, Los Angeles, California 90095, USA. vkick@mednet.ucla.edu
Stephen
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Harrington
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Robinson
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Rome
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D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry*; D002499:Centrifugation, Density Gradient; D004268:DNA-Binding Proteins; D000882:Haplorhini; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D011233:Precipitin Tests; D011485:Protein Binding; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics; D019098:Telomerase / Q000737:chemistry* / Q000378:metabolism; D020394:Vault Ribonucleoprotein Particles / Q000737:chemistry* / Q000235:genetics; D015003:Yeasts
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C104342:TEP1 protein, human; C498415:Tep1 protein, mouse; D020394:Vault Ribonucleoprotein Particles; C422952:telomerase RNA; D012313:RNA; D019098:Telomerase; C498417:telomerase p80 protein, Tetrahymena