Ca (2+) -dependent effects of C-protein on the actin-activated ATPase of phosphorylated and dephosphorylated skeletal muscle myosin
Udaltsov, S.N.; Stepkowski, D.; Freydina, N.A.; Podlubnaya, Z.A.
Biochemistry International 25(5): 837-843
1991
ISSN/ISBN: 0158-5231 PMID: 1839495 Document Number: 385827
The effects of C-protein on actin-activated myosin ATPase depending on Ca(2+)-level and LC2-phosphorylation were studied. Column-purified myosin and non-regulated actin were used. At ionic strength of 0.06 C-protein inhibits actomyosin ATPase activity both in the presence and in the absence of calcium, more effective in the case of dephosphorylated myosin. For this myosin, at mu = 0.12 C-protein activates actomyosin ATPase at pCa4, but slightly inhibits at pCa8. No such effects have been observed in the case of phosphorylated myosin. The possibility of coordinative action of LC2-chains and C-protein in regulatory mechanism of skeletal muscle contraction is discussed.