Komatsu S, Hosoya H
Department of Biological Science, Faculty of Science, Hiroshima University, Japan.
Biochem Biophys Res Commun. 1996 Jun 25;223(3):741-5. doi: 10.1006/bbrc.1996.0966.
Mitogen-activated protein kinase activated protein (MAPKAP) kinase-2 was found to phosphorylate the regulatory light chain of myosin II (MRLC) in vitro in the absence of Ca2+/calmodulin. The tryptic peptides recovered from the MRLC phosphorylated by MAPKAP kinase-2 were identical to the phosphopeptides recovered from myosin light chain kinase (MLCK)-phosphorylated MRLC. Phosphoamino acid analysis revealed that MRLC was phosphorylated by these kinases at the serine residue. This phosphorylation by MAPKAP kinase-2 activated the actin-activated Mg(2+)-ATPase activity of myosin II. These findings indicated that MAPKAP kinase-2 may be a kinase that regulates the actin-activated Mg(2+)-ATPase activity of myosin II.
丝裂原活化蛋白激酶激活蛋白（MAPKAP）激酶-2被发现可在体外无Ca2+/钙调蛋白的情况下使肌球蛋白II（MRLC）的调节轻链磷酸化。从被MAPKAP激酶-2磷酸化的MRLC中回收的胰蛋白酶肽段与从肌球蛋白轻链激酶（MLCK）磷酸化的MRLC中回收的磷酸肽段相同。磷酸氨基酸分析表明，MRLC被这些激酶在丝氨酸残基处磷酸化。MAPKAP激酶-2的这种磷酸化激活了肌球蛋白II的肌动蛋白激活的Mg(2+)-ATP酶活性。这些发现表明，MAPKAP激酶-2可能是一种调节肌球蛋白II的肌动蛋白激活的Mg(2+)-ATP酶活性的激酶。
