Mitosis-specific Phosphorylation of Smooth Muscle Regulatory Light Chain of Myosin II at Ser-1 and/or -2 and Thr-9 in Sea Urchin Egg Extract

Cell Structure and Function

Eiko Himi-Nakamura¹  Hikoichi Sakai²  Go Totsukawa¹  Hiroshi Hosoya¹  Kazumori Yazaki³  Ayako Tezuka²  Kyoko Iwata²  Satoshi Komatsu¹ 

[1]Department of Biological Science, Faculty of Science, Hiroshima University

[2]Department of Chemical and Biological Sciences, Faculty of Science, Japan Women's University

[3]Department of Ultrastructual Research, The Tokyo Metropolitan Institute of Medical Science

关键词: myosin regulatory light chain;    MLCK;    cdc2 kinase;    phosphorylation;    sea urchin;    cell cycle;   

DOI  :  10.1247/csf.21.475

学科分类：分子生物学，细胞生物学和基因

来源: Japan Society for Cell Biology

【 摘 要 】

References(32)Cited-By(10)We analyzed the kinase activities capable of phosphorylating the regulatory light chain of myosin-II (MRLC) from chicken gizzard in unfertilized and fertilized sea urchin egg extracts. Total kinase activity phosphorylating MRLC in vitro did not fluctuate throughout the first cell cycle. Phosphopeptide mapping analysis showed that MRLC was phosphorylated at two different sites corresponding to myosin light chain kinase purified from chicken gizzard (MLCK) and protein kinase C (PKC) phosphorylation sites, namely MLCK and PKC sites, respectively. The activity of the kinase(s) responsible for phosphorylation of MRLC at PKC sites showed a significant increase at metaphase. Phosphoamino acid analysis revealed that this increase in MRLC phosphorylation was due to phosphorylation at serine residue (Ser-1 and/or Ser-2) and at threonine residue (Thr-9). This increase in phosphorylation at PKC sites is occurred concomitantly with an increase in histone HI kinase activity. In contrast, MRLC phosphorylation at MLCK sites showed no significant changes during the first cell cycle. Butyrolactone I, a selective inhibitor of p34cdc2 kinase, inhibited the activity of the kinase(s) responsible for phosphorylation of MRLC at PKC sites at metaphase. These results suggest that the increase in MRLC phosphorylation at PKC sites (Ser-1 and/or -2, and Thr-9) at metaphase may be induced by p34cdc2 kinase. Thus, p34cdc2 kinase may be involved in the regulation of MRLC phosphorylation during cell division.

【 授权许可】

Unknown