TY - JOUR
T1 - Purification and characterization of myosin light-chain kinase from porcine myometrium and its phosphorylation and modulation by cyclic amp-dependent protein kinase
AU - Higashi, Kenji
AU - Fukunaga, Kohji
AU - Matsui, Kazuo
AU - Maeyama, Masao
AU - Miyamoto, Eishichi
N1 - Funding Information:
This work was supported in part by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan, 1982-1983. We are grateful to T. Muramatsu for secretarial services.
PY - 1983/9/28
Y1 - 1983/9/28
N2 - Myosin light-chain kinase was purified from porcine myometrium to apparent homogeneity at about 262-fold with an Mr of 130 000 as determined by SDS-polyacrylamide gel electrophoresis and a sedimentation coefficient of 4.5 S. The approximate content of the soluble myosin light-chain kinasee was estimated to be about 0.85 μ M. The purified enzyme exhibited strict substrate specificity only for 20-kDa myosin light chain and a values of 0.6 nM and 0.3 μM for calmodulin and Ca2+, respectively. The enzyme was phosphorylated by the catalytic subunit of cyclic AMP-dependent protein kinase, which resulted in a decrease in the affinity for calmodulin of 4-7-fold without effect on the Vmax. The maximal amount of phosphate incorporated into the enzyme was 0.5-0.8 and 1.0-1.4 mol per mol of the enzme in the presence and absence of Ca2+ and calmodulin, respectively. In the presence of a subsaturating concentration of calmodulin, the enzyme showed a lower sensitivity for Ca2+ by phosphorylation.
AB - Myosin light-chain kinase was purified from porcine myometrium to apparent homogeneity at about 262-fold with an Mr of 130 000 as determined by SDS-polyacrylamide gel electrophoresis and a sedimentation coefficient of 4.5 S. The approximate content of the soluble myosin light-chain kinasee was estimated to be about 0.85 μ M. The purified enzyme exhibited strict substrate specificity only for 20-kDa myosin light chain and a values of 0.6 nM and 0.3 μM for calmodulin and Ca2+, respectively. The enzyme was phosphorylated by the catalytic subunit of cyclic AMP-dependent protein kinase, which resulted in a decrease in the affinity for calmodulin of 4-7-fold without effect on the Vmax. The maximal amount of phosphate incorporated into the enzyme was 0.5-0.8 and 1.0-1.4 mol per mol of the enzme in the presence and absence of Ca2+ and calmodulin, respectively. In the presence of a subsaturating concentration of calmodulin, the enzyme showed a lower sensitivity for Ca2+ by phosphorylation.
KW - (Procine myometrium)
KW - Calmodulin sensitivity
KW - Myosin light-chain kinase
KW - Phosphorylation
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U2 - 10.1016/0167-4838(83)90102-4
DO - 10.1016/0167-4838(83)90102-4
M3 - Article
C2 - 6311271
AN - SCOPUS:0021114431
VL - 747
SP - 232
EP - 240
JO - BBA - Protein Structure
JF - BBA - Protein Structure
SN - 1570-9639
IS - 3
ER -