Regulation of c-Src by binding to the PDZ domain of AF-6.
c-Src is a tightly regulated non-receptor tyrosine kinase. We describe the C-terminus of c-Src as a ligand for a PDZ (postsynaptic density 95, PSD-95; discs large, Dlg; zonula occludens-1, ZO-1) domain. The C-terminal residue Leu of c-Src is essential for binding to a PDZ domain. Mutation of this residue does not affect the intrinsic kinase activity in vitro, but interferes with c-Src regulation in cells. As a candidate PDZ protein, we analysed AF-6, a junctional adhesion protein. The AF-6 PDZ domain restricts the number of c-Src substrates, whereas knockdown of AF-6 has the opposite effect. Binding of c-Src to the AF-6 PDZ domain interferes with phosphorylation of c-Src at Tyr527 by the C-terminal kinase, and reduces c-Src autophosphorylation at Tyr416, resulting in a moderately activated c-Src kinase. Unphosphorylated Tyr527 allows binding of c-Src to AF-6. This can be overcome by overexpression of CSK or strong activation of c-Src. c-Src is recruited by AF-6 to cell-cell contact sites, suggesting that c-Src is regulated by a PDZ protein in special cellular locations. We identified a novel type of c-Src regulation by interaction with a PDZ protein.
Radziwill
Gerald
G
Institute of Medical Virology, University of Zurich, Zurich, Switzerland. radziwil@immv.unizh.ch
Weiss
Andreas
A
Heinrich
Jochen
J
Baumgartner
Martin
M
Boisguerin
Prisca
P
Owada
Koji
K
Moelling
Karin
K
D000595:Amino Acid Sequence; D000081247:CSK Tyrosine-Protein Kinase; D004789:Enzyme Activation / Q000235:genetics; D040461:Gene Components; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009218:Myosins / Q000235:genetics / Q000378:metabolism*; D054731:PDZ Domains / Q000235:genetics*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D019061:src-Family Kinases
C095516:AFDN protein, human; D011518:Proto-Oncogene Proteins; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; C000631346:CSK protein, human; D009218:Myosins; D016547:Kinesins