The luminal domain of TGN38 interacts with integrin beta 1 and is involved in its trafficking.
TGN38 luminal domain (TGN38LD) was expressed in Cos-7 cells to identify potential binding partners. The luminal domain was secreted but, surprisingly, a significant portion bound to the plasma membrane. Cells overexpressing TGN38LD or the full-length molecule detached from the substratum and left footprints positive for TGN38. Unexpectedly, in these cells, TGN38 colocalizes with integrin alpha 5 beta 1 at the Golgi, the cell surface or in the footprints and an increased amount of both integrin subunits on the plasma membrane was observed. Under physiological conditions when TGN38 is not overexpressed, it interacts with integrin beta 1. This was demonstrated by reciprocal co-immunoprecipitation of integrin beta 1 and TGN38. Functional analysis reveals that modification of the trafficking of TGN38 results in a parallel change in the distribution of integrin alpha 5 beta 1, leading to the conclusion that TGN38 is involved in the trafficking of integrin beta 1.
Wang
J
J
Department of Cellular & Structural Biology, Box B-111, University of Colorado School of Medicine, 4200 E 9th Ave., Denver, CO 80262, USA.
Howell
K E
KE
D000818:Animals; D019556:COS Cells / Q000378:metabolism / Q000648:ultrastructure; D002448:Cell Adhesion / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D006023:Glycoproteins; D006031:Glycosylation; D019012:Integrin beta1 / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D021381:Protein Transport / Q000502:physiology*; D021601:trans-Golgi Network / Q000378:metabolism*
D006023:Glycoproteins; D019012:Integrin beta1; D008562:Membrane Glycoproteins; D008565:Membrane Proteins