title: TBC1D13 is a RAB35 specific GAP that plays an important role in GLUT4 trafficking in adipocytes.
abstract: Insulin stimulates glucose transport in adipocytes by triggering translocation of GLUT4 glucose transporters to the plasma membrane (PM) and several Rabs including Rab10 have been implicated in this process. To delineate the molecular regulation of this pathway, we conducted a TBC/RabGAP overexpression screen in adipocytes. This identified TBC1D13 as a potent inhibitor of insulin-stimulated GLUT4 translocation without affecting other trafficking pathways. To determine the potential Rab substrate for TBC1D13 we conducted a yeast two-hybrid screen and found that the GTP bound forms of Rabs 1 and 10 specifically interacted with TBC1D13 but not with eight other TBC proteins. Surprisingly, a comprehensive in vitro screen for TBC1D13 GAP activity revealed Rab35 but not Rab10 as a specific substrate. TBC1D13 also displayed in vivo GAP activity towards Rab35. Overexpression of constitutively active Rab35 but not constitutively active Rab10 reversed the block in insulin-stimulated GLUT4 translocation observed with TBC1D13 overexpression. These studies implicate an important role for Rab35 in insulin-stimulated GLUT4 translocation in adipocytes.
authors: Diabetes and Obesity Program, Garvan Institute of Medical Research, Sydney, 2010, Australia; St Vincent's Clinical School, University of New South Wales, Sydney, 2052, Australia.
authors: Jonathan R
authors: JR
authors: Davey
authors: Sean J
authors: SJ
authors: Humphrey
authors: Jagath R
authors: JR
authors: Junutula
authors: Ashwini K
authors: AK
authors: Mishra
authors: David G
authors: DG
authors: Lambright
authors: David E
authors: DE
authors: James
authors: Jacqueline
authors: J
authors: Stöckli
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D051275:Glucose Transporter Type 4 / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007328:Insulin / Q000378:metabolism; D051379:Mice; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D020691:rab GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D020690:GTPase-Activating Proteins; D051275:Glucose Transporter Type 4; D007328:Insulin; D009687:Nuclear Proteins; C095906:Tbc1d1 protein, mouse; C543587:Rab35 protein, mouse; D020691:rab GTP-Binding Proteins