Serum-activated assembly and membrane translocation of an endogenous Rac1:effector complex.
Rho family GTPases (Cdc42, Rac1, and RhoA) function downstream of Ras [1], and in a variety of cellular processes [2]. Studies to examine these functions have not directly linked endogenous protein interactions with specific in vivo functions of Rho GTPases. Here, we show that endogenous Rac1 and two known binding partners, Rho GDP dissociation inhibitor (RhoGDI) and p21-activated kinase (PAK), fractionate as distinct cytosolic complexes. A Rac1:PAK complex is translocated from the cytosol to ruffling membranes upon cell activation by serum. Overexpression of dominant-negative (T17N) Rac1 does not affect the assembly or distribution of this Rac1:PAK complex. This is the first direct evidence of how a specific function of Rac1 is selected by the assembly and membrane translocation of a distinct Rac1:effector complex.
Hansen
M D
MD
Department of Molecular and Cellular Physiology, Beckman Center for Molecular and Genetic Medicine, Stanford University School of Medicine, Stanford, CA 94305-5345, USA.
Nelson
W J
WJ
D000818:Animals; D001692:Biological Transport; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003470:Culture Media; D003600:Cytosol / Q000378:metabolism; D004285:Dogs; D004789:Enzyme Activation; D020730:Guanine Nucleotide Dissociation Inhibitors / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012709:Serum Albumin; D054462:p21-Activated Kinases; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors
D003470:Culture Media; D020730:Guanine Nucleotide Dissociation Inhibitors; D012709:Serum Albumin; D062947:rho-Specific Guanine Nucleotide Dissociation Inhibitors; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; D020830:rac1 GTP-Binding Protein