title: Screening for target Rabs of TBC (Tre-2/Bub2/Cdc16) domain-containing proteins based on their Rab-binding activity.
abstract: It has recently been proposed that the TBC (Tre2/Bub2/Cdc16) domain functions as a GAP (GTPase-activating protein) domain for small GTPase Rab. Because of the large number of Rab proteins in mammals, however, most TBC domains have never been investigated for Rab-GAP activity. In this study we established panels of the GTP-fixed form of 60 different Rabs constructed in pGAD-C1, a yeast two-hybrid bait vector. We also constructed a yeast two-hybrid prey vector (pGBDU-C1) that harbors the cDNA of 40 distinct TBC proteins. Systematic investigation of 2400 combinations of 60 GTP-fixed Rabs and 40 TBC proteins by yeast two-hybrid screening revealed that seven TBC proteins specifically and differentially interact with specific Rabs (e.g. OATL1 interacts with Rab2A; FLJ12085 with Rab5A/B/C; and Evi5-like with Rab10). Measurement of in vitro Rab-GAP activity revealed that OATL1 and Evi5-like actually possess significant Rab2A- and Rab10-GAP activity, respectively, but that FLJ12085 do not display Rab5A-GAP activity at all. These results indicate that specific interaction between TBC protein and Rab would be a useful indicator for screening for the target Rabs of some TBC/Rab-GAP domains, but that there is little correlation between the Rab-binding activity and Rab-GAP activity of other TBC proteins.
authors.affiliation: Fukuda Initiative Research Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Itoh
authors.forename: Megumi
authors.initials: M
authors.lastname: Satoh
authors.forename: Eiko
authors.initials: E
authors.lastname: Kanno
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Fukuda
mesh_terms: D000818:Animals; D019556:COS Cells; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism*; D002522:Chlorocebus aethiops; D020690:GTPase-Activating Proteins / Q000378:metabolism; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D009687:Nuclear Proteins / Q000378:metabolism; D010802:Phylogeny; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D014157:Transcription Factors / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; C506399:EVI5 protein, human; C105043:Evi5 protein, mouse; D020690:GTPase-Activating Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; D020691:rab GTP-Binding Proteins