A protein kinase from neutrophils that specifically recognizes Ser-3 in cofilin.
Cofilin promotes the depolymerization of actin filaments, which is required for a variety of cellular responses such as the formation of lamellipodia and chemotaxis. Phosphorylation of cofilin on serine residue 3 is known to block these activities. We now report that neutrophils contain a protein kinase that selectively catalyzes the phosphorylation of cofilin on serine 3 (>/=70%) and a nonspecific kinase that recognizes multiple sites in this protein. The selective serine 3 cofilin kinase binds to a deoxyribonuclease I affinity column, whereas the nonspecific cofilin kinase does not. Deoxyribonuclease I forms a very tight complex with actin, and deoxyribonuclease affinity columns have been utilized to identify a variety of proteins that interact with the cytoskeleton. The serine 3 cofilin kinase did not react with antibodies to LIM kinase 1 or 2, which can catalyze the phosphorylation of cofilin in other cell types. The activity of the serine 3 cofilin kinase was insensitive to a variety of selective antagonists of protein kinases but was blocked by staurosporine. This pattern of inhibition is similar to that observed for the kinase that is active with cofilin in intact neutrophils. Thus, neutrophils contain a protein kinase distinct from LIM kinase-1/2 that selectively recognizes serine 3 in cofilin.
Lian
J P
JP
Center for Experimental Therapeutics and Reperfusion Injury, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
Marks
P G
PG
Wang
J Y
JY
Falls
D L
DL
Badwey
J A
JA
D051339:Actin Depolymerizing Factors; D000595:Amino Acid Sequence; D000818:Animals; D002384:Catalysis; D004268:DNA-Binding Proteins / Q000378:metabolism; D006168:Guinea Pigs; D006801:Humans; D054461:Lim Kinases; D008840:Microfilament Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000201:enzymology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012694:Serine / Q000378:metabolism*; D013379:Substrate Specificity
D051339:Actin Depolymerizing Factors; D004268:DNA-Binding Proteins; D008840:Microfilament Proteins; D011994:Recombinant Proteins; D012694:Serine; D011494:Protein Kinases; C515892:LIMK1 protein, human; D054461:Lim Kinases; D017346:Protein Serine-Threonine Kinases