• We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Logo of pnasPNASInfo for AuthorsSubscriptionsAboutThis Article
Proc Natl Acad Sci U S A. Apr 1979; 76(4): 1653–1657.
PMCID: PMC383448

Human platelet myosin light chain kinase requires the calcium-binding protein calmodulin for activity.


In an actomyosin fraction isolated from human platelets, phosphorylation of the 20,000-dalton light chain of myosin is stimulated by calcium and the calcium-binding protein calmodulin. The enzyme catalyzing this phosphorylation has been isolated by using calmodulin-affinity chromatography. Platelet myosin light chain kinase activity was monitored throughout the isolation procedures by using the 20,000-dalton smooth muscle myosin light chain purified from turkey gizzards as substrate. The partially purified myosin kinase requires both calcium and calmodulin for activity and has a specific activity of 3.1 mumol of phosphate transferred to the 20,000-dalton light chain per mg of kinase per min under optimal assay conditions. Km values determined for ATP and myosin light chains are 121 microM and 18 microM, respectively. Of several substrates surveyed as phosphate acceptors (alpha-casein, histone II-A, phosphorylase b, protamine, histone V-S, and phosvitin), only the 20,000-dalton myosin light chain is phosphorylated at a significant rate. These results suggest that platelet myosin light chain kinase is a calcium-dependent enzyme and that the requirement for calcium is mediated by the calcium-binding protein calmodulin.

Full text

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (1.0M), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References.

Images in this article

Click on the image to see a larger version.

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Korn ED. Biochemistry of actomyosin-dependent cell motility (a review). Proc Natl Acad Sci U S A. 1978 Feb;75(2):588–599. [PMC free article] [PubMed]
  • Adelstein RS, Conti MA. Phosphorylation of platelet myosin increases actin-activated myosin ATPase activity. Nature. 1975 Aug 14;256(5518):597–598. [PubMed]
  • Chacko S, Conti MA, Adelstein RS. Effect of phosphorylation of smooth muscle myosin on actin activation and Ca2+ regulation. Proc Natl Acad Sci U S A. 1977 Jan;74(1):129–133. [PMC free article] [PubMed]
  • Sobieszek A. Ca-linked phosphorylation of a light chain of vertebrate smooth-muscle myosin. Eur J Biochem. 1977 Mar 1;73(2):477–483. [PubMed]
  • Górecka A, Aksoy MO, Hartshorne DJ. The effect of phosphorylation of gizzard myosin on actin activation. Biochem Biophys Res Commun. 1976 Jul 12;71(1):325–331. [PubMed]
  • Scordilis SP, Adelstein RS. Myoblast myosin phosphorylation is a prerequisite for actin-activation. Nature. 1977 Aug 11;268(5620):558–560. [PubMed]
  • Weber A, Murray JM. Molecular control mechanisms in muscle contraction. Physiol Rev. 1973 Jul;53(3):612–673. [PubMed]
  • Dabrowska R, Aromatorio D, Sherry JM, Hartshorne DJ. Composition of the myosin light chain kinase from chicken gizzard. Biochem Biophys Res Commun. 1977 Oct 24;78(4):1263–1272. [PubMed]
  • Dabrowska R, Sherry JM, Aromatorio DK, Hartshorne DJ. Modulator protein as a component of the myosin light chain kinase from chicken gizzard. Biochemistry. 1978 Jan 24;17(2):253–258. [PubMed]
  • Daniel JL, Adelstein RS. Isolation and properties of platelet myosin light chain kinase. Biochemistry. 1976 Jun 1;15(11):2370–2377. [PubMed]
  • Fairbanks G, Steck TL, Wallach DF. Electrophoretic analysis of the major polypeptides of the human erythrocyte membrane. Biochemistry. 1971 Jun 22;10(13):2606–2617. [PubMed]
  • Laemmli UK. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. [PubMed]
  • Klee CB. Conformational transition accompanying the binding of Ca2+ to the protein activator of 3',5'-cyclic adenosine monophosphate phosphodiesterase. Biochemistry. 1977 Mar 8;16(5):1017–1024. [PubMed]
  • Klee CB, Krinks MH. Purification of cyclic 3',5'-nucleotide phosphodiesterase inhibitory protein by affinity chromatography on activator protein coupled to Sepharose. Biochemistry. 1978 Jan 10;17(1):120–126. [PubMed]
  • LOWRY OH, ROSEBROUGH NJ, FARR AL, RANDALL RJ. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed]
  • Perrie WT, Perry SV. An electrophoretic study of the low-molecular-weight components of myosin. Biochem J. 1970 Aug;119(1):31–38. [PMC free article] [PubMed]
  • Lyons RM, Stanford N, Majerus PW. Thrombin-induced protein phosphorylation in human platelets. J Clin Invest. 1975 Oct;56(4):924–936. [PMC free article] [PubMed]
  • Daniel JL, Holmsen H, Adelstein RS. Thrombin-stimulated myosin phosphorylation in intact platelets and its possible involvement secretion. Thromb Haemost. 1977 Dec 15;38(4):984–989. [PubMed]
  • Haslam RJ, Lynham JA. Relationship between phosphorylation of blood platelet proteins and secretion of platelet granule constituents. I. Effects of different aggregating agents. Biochem Biophys Res Commun. 1977 Jul 25;77(2):714–722. [PubMed]
  • Muszbek L, Kuznicki J, Szabó T, Drabikowski W. Troponin C like protein of blood platelets. FEBS Lett. 1977 Aug 15;80(2):308–312. [PubMed]
  • Lin YM, Liu YP, Cheung WY. Cyclic 3',5'-nucleotide phosphodiesterase Ca++-dependent formation of bovine brain enzyme-activator complex. FEBS Lett. 1975 Jan 1;49(3):356–360. [PubMed]
  • Yazawa M, Yagi K. Calcium-binding subunit of myosin light chain kinase. J Biochem. 1977 Jul;82(1):287–289. [PubMed]
  • Nairn AC, Perry SV. Calmodulin and myosin light-chain kinase of rabbit fast skeletal muscle. Biochem J. 1979 Apr 1;179(1):89–97. [PMC free article] [PubMed]
  • Waisman DM, Singh TJ, Wang JH. The modulator-dependent protein kinase. A multifunctional protein kinase activatable by the Ca2+-dependent modulator protein of the cyclic nucleotide system. J Biol Chem. 1978 May 25;253(10):3387–3390. [PubMed]
  • Cheung WY. Cyclic 3',5'-nucleotide phosphodiesterase: pronounced stimulation by snake venom. Biochem Biophys Res Commun. 1967 Nov 30;29(4):478–482. [PubMed]
  • Brostrom CO, Huang YC, Breckenridge BM, Wolff DJ. Identification of a calcium-binding protein as a calcium-dependent regulator of brain adenylate cyclase. Proc Natl Acad Sci U S A. 1975 Jan;72(1):64–68. [PMC free article] [PubMed]
  • Gopinath RM, Vincenzi FF. Phosphodiesterase protein activator mimics red blood cell cytoplasmic activator of (Ca2+-Mg2+)ATPase. Biochem Biophys Res Commun. 1977 Aug 22;77(4):1203–1209. [PubMed]
  • Jarrett HW, Penniston JT. Partial purification of the Ca2+-Mg2+ ATPase activator from human erythrocytes: its similarity to the activator of 3':5' - cyclic nucleotide phosphodiesterase. Biochem Biophys Res Commun. 1977 Aug 22;77(4):1210–1216. [PubMed]
  • Luthra MG, Au KS, Hanahan DJ. Purification of an activator of human erythrocyte membrane (Ca2++Mg2+)ATPase. Biochem Biophys Res Commun. 1977 Jul 25;77(2):678–687. [PubMed]
  • Cohen P, Burchell A, Foulkes JG, Cohen PT, Vanaman TC, Nairn C. Identification of the Ca2+-dependent modulator protein as the fourth subunit of rabbit skeletal muscle phosphorylase kinase. FEBS Lett. 1978 Aug 15;92(2):287–293. [PubMed]
  • Schulman H, Greengard P. Stimulation of brain membrane protein phosphorylation by calcium and an endogenous heat-stable protein. Nature. 1978 Feb 2;271(5644):478–479. [PubMed]
  • Marcum JM, Dedman JR, Brinkley BR, Means AR. Control of microtubule assembly-disassembly by calcium-dependent regulator protein. Proc Natl Acad Sci U S A. 1978 Aug;75(8):3771–3775. [PMC free article] [PubMed]
  • Dabrowska R, Hartshorne DJ. A Ca2+-and modulator-dependent myosin light chain kinase from non-muscle cells. Biochem Biophys Res Commun. 1978 Dec 29;85(4):1352–1359. [PubMed]
  • Yerna MJ, Dabrowska R, Hartshorne DJ, Goldman RD. Calcium-sensitive regulation of actin-myosin interactions in baby hamster kidney (BHK-21) cells. Proc Natl Acad Sci U S A. 1979 Jan;76(1):184–188. [PMC free article] [PubMed]

Articles from Proceedings of the National Academy of Sciences of the United States of America are provided here courtesy of National Academy of Sciences


Related citations in PubMed

See reviews...See all...

Cited by other articles in PMC

See all...


  • Compound
    PubChem Compound links
  • MedGen
    Related information in MedGen
  • PubMed
    PubMed citations for these articles
  • Substance
    PubChem Substance links

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...