Interaction of paxillin with p21-activated Kinase (PAK). Association of paxillin alpha with the kinase-inactive and the Cdc42-activated forms of PAK3.
p21-activated kinases (PAKs) are implicated in integrin signalings, and have been proposed to associate with paxillin indirectly. We show here that paxillin can bind directly to PAK3. We examined several representative focal adhesion proteins, and found that paxillin is the sole protein that associates with PAK3. PAK3 associated with the alpha and beta isoforms of paxillin, but not with gamma. We also show that paxillin alpha associated with both the kinase-inactive and the Cdc42-activated forms of PAK3 in vivo, without affecting the activation states of the kinase. A number of different functions have been ascribed to PAKs; and PAKs can bind directly to growth factor signaling-adaptor molecule, Nck, and a guanine nucleotide exchanger, betaPIX. Our results revealed that paxillin alpha can compete with Nck and betaPIX in the binding of PAK3. Moreover, paxillin alpha can be phosphorylated by PAK3 at serine. Therefore, paxillin alpha, but not gamma, appears to be capable of linking both the kinase-inactive and activated forms of PAK3 to integrins independent of Nck and betaPIX, as Nck links PAK1 to growth factor receptors. Our results also revealed that paxillin is involved in highly complexed protein-protein interactions in integrin signaling.
Hashimoto
S
S
Department of Molecular Biology, Osaka Bioscience Institute, Suita, Osaka 565-0874, Japan.
Tsubouchi
A
A
Mazaki
Y
Y
Sabe
H
H
D048868:Adaptor Proteins, Signal Transducing; D001665:Binding Sites; D001667:Binding, Competitive; D018797:Cell Cycle Proteins / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004789:Enzyme Activation; D051418:Focal Adhesion Kinase 2; D051416:Focal Adhesion Protein-Tyrosine Kinases; D022001:Focal Adhesions; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism; D015513:Oncogene Proteins / Q000378:metabolism; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism*; D011485:Protein Binding; D020033:Protein Isoforms / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins; D050717:Retinoblastoma-Like Protein p130; D064067:Rho Guanine Nucleotide Exchange Factors; D016608:Talin / Q000378:metabolism; D000070876:Tensins; D016596:Vinculin / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D054462:p21-Activated Kinases
D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D020662:Guanine Nucleotide Exchange Factors; D008840:Microfilament Proteins; C078332:Nck protein; D015513:Oncogene Proteins; D051419:Paxillin; D010750:Phosphoproteins; D020033:Protein Isoforms; D011506:Proteins; D050717:Retinoblastoma-Like Protein p130; D064067:Rho Guanine Nucleotide Exchange Factors; D016608:Talin; D000070876:Tensins; D016596:Vinculin; D011505:Protein-Tyrosine Kinases; D051418:Focal Adhesion Kinase 2; D051416:Focal Adhesion Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; D020764:cdc42 GTP-Binding Protein