Phosphorylation of brush border myosin at threonine on its 20 kDa light chains by a calmodulin-independent kinase activates its ATPase.
A calmodulin-independent kinase isolated from chicken intestinal brush border phosphorylates brush border myosin mainly at an apparently single threonine on its 20 kDa light chains. Phosphorylation to 1.9 mol phosphate/mol myosin activated the myosin actin-activated ATPase about 12-fold, to about 100 nmol/min per mg. Brush border myosin ATPase can thus be activated by phosphorylation either at threonine, by calmodulin-independent kinase, or at serine, by calmodulin-dependent myosin light chain kinase, as previously shown [(1987) FEBS Lett. 223, 262-266].
Borysenko
C
C
Department of Microbiology, Biochemistry and Molecular Biology, School of Medicine, University of Pittsburgh, PA 15261.
Rieker
J P
JP
Swanljung-Collins
H
H
Montibeller
J
J
Collins
J H
JH
D000199:Actins / Q000494:pharmacology; D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000494:pharmacology; D002645:Chickens; D004533:Egtazic Acid / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D007422:Intestines / Q000032:analysis*; D008871:Microvilli / Q000032:analysis; D009218:Myosins / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D010769:Phosphothreonine / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism*; D013912:Threonine / Q000031:analogs & derivatives*; D014357:Trypsin
D000199:Actins; D002147:Calmodulin; D010446:Peptide Fragments; D010769:Phosphothreonine; D010768:Phosphoserine; D013912:Threonine; D004533:Egtazic Acid; D011494:Protein Kinases; D014357:Trypsin; D000251:Adenosine Triphosphatases; D009218:Myosins; D002118:Calcium