p21-activated kinase PAK phosphorylates desmin at sites different from those for Rho-associated kinase.
p21-activated kinase (PAK) and Rho-associated kinase (Rho-kinase) have been shown to induce Ca(2+)-independent contraction of smooth muscle. PAK-induced contraction of Triton-skinned smooth muscle correlates with increased phosphorylation of caldesmon and desmin, although the role of desmin phosphorylation has remained obscure. Here we report that desmin serves as an excellent substrate for PAK in vitro. PAK phosphorylated desmin in a GTP. Cdc42/Rac-dependent manner. Phosphorylation of desmin by PAK dramatically inhibited its filament-forming ability. PAK phosphorylated mainly serine residues of the head domain of desmin, and the major phosphorylation sites differed from those for Rho-kinase. These results suggest that different site-specific phosphorylation of desmin via two divergent protein kinases downstream of Rho family GTPases would seem to increase the regulatory potential for organization of desmin filaments.
Ohtakara
K
K
Division of Biochemistry, Aichi Cancer Center Research Institute, Nagoya, Japan.
Inada
H
H
Goto
H
H
Taki
W
W
Manser
E
E
Lim
L
L
Izawa
I
I
Inagaki
M
M
D000818:Animals; D003893:Desmin / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D004789:Enzyme Activation; D006160:Guanosine Triphosphate / Q000378:metabolism; D007382:Intermediate Filaments / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D008970:Molecular Weight; D010449:Peptide Mapping; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D054462:p21-Activated Kinases; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D003893:Desmin; D047908:Intracellular Signaling Peptides and Proteins; D011993:Recombinant Fusion Proteins; D010768:Phosphoserine; D006160:Guanosine Triphosphate; C515913:Pak3 protein, rat; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; D054460:rho-Associated Kinases; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein