scholarly journals Purification and properties of myosin light-chain kinase from fast skeletal muscle

1977 ◽  
Vol 167 (1) ◽  
pp. 137-146 ◽  
Author(s):  
E M V Pires ◽  
S V Perry
Keyword(s):  
Skeletal Muscle ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Similar Rate ◽  
Enzymic Activity ◽  
Fast Skeletal Muscle ◽  
Bivalent Cation ◽  
Purification And Properties ◽  
Effects Of Ph

1. A procedure is described for the isolation of myosin light-chain kinase from rabbit fast skeletal muscle as a homogeneous protein. 2. Myosin light-chain kinase is a monomeric enzyme of mol.wt. 77000. Under some conditions of storage it is converted into components of mol.wts. about 50000 and 30000 that possess enzymic activity. 3. The enzyme is clearly different in structure and properties from any other protein kinase so far isolated from muscle. 4. The enzyme is highly specific for the P-light chain (18000-20000-dalton light chain) of myosin and requires Ca2+ for activity. 5. The P-light chain is phosphorylated at a similar rate whether isolated or associated with the rest of the myosin molecule. 6. The effects of pH, bivalent cation and other nucleotides on the enzymic activity are described. 7. The role of the phosphorylation of the P-light chain of myosin in muscle function is discussed.

scholarly journals Calmodulin and myosin light-chain kinase of rabbit fast skeletal muscle

1979 ◽  
Vol 179 (1) ◽  
pp. 89-97 ◽  
Author(s):  
A C Nairn ◽  
S V Perry
Keyword(s):  
Skeletal Muscle ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Troponin I ◽  
Maximal Activity ◽  
Bovine Brain ◽  
Affinity Column ◽  
Fast Skeletal Muscle ◽  
Skeletal Muscle Myosin

1. It is confirmed that myosin light-chain kinase is a protein of mol.wt. about 80,000 that is inactive in the absence of calmodulin. 2. In the presence of 1 mol of calmodulin/mol of kinase 80-90% of the maximal activity is obtained. 3. Crude preparations of the whole light-chain fraction of rabbit fast-skeletal-muscle myosin contain enough calmodulin to activate the enzyme. A method for the preparation of calmodulin-free P light chain is described. 4. A procedure is described for the isolation of calmodulin from rabbit fast skeletal muscle. 5. Rabbit fast-skeletal-muscle calmodulin is indistinguishable from bovine brain calmodulin in its ability to activate myosin light-chain kinase. The other properties of these two proteins are also very similar. 6. Rabbit fast-skeletal-muscle troponin C was about 10% as effective as calmodulin as activator for myosin light-chain kinase. 7. By chromatography on a Sepharose-calmodulin affinity column evidence was obtained for the formation of a Ca2+-dependent complex between calmodulin and myosin light-chain kinase. 8. Troponin I from rabbit fast skeletal muscle and histone IIAS were phosphorylated by fully activated myosin light-chain kinase at about 1% of the rate of the P light chain.

scholarly journals Smooth muscle myosin light chain kinase expression in cardiac and skeletal muscle

2000 ◽  
Vol 279 (5) ◽  
pp. C1656-C1664 ◽  
Author(s):  
B. Paul Herring ◽  
Shelley Dixon ◽  
Patricia J. Gallagher
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Cardiac Myocyte ◽  
Cardiac Tissue ◽  
Specific Protein ◽  
Myoblast Differentiation ◽  
Adult Skeletal Muscle

The purpose of this study was to characterize myosin light chain kinase (MLCK) expression in cardiac and skeletal muscle. The only classic MLCK detected in cardiac tissue, purified cardiac myocytes, and in a cardiac myocyte cell line (AT1) was identical to the 130-kDa smooth muscle MLCK (smMLCK). A complex pattern of MLCK expression was observed during differentiation of skeletal muscle in which the 220-kDa-long or “nonmuscle” form of MLCK is expressed in undifferentiated myoblasts. Subsequently, during myoblast differentiation, expression of the 220-kDa MLCK declines and expression of this form is replaced by the 130-kDa smMLCK and a skeletal muscle-specific isoform, skMLCK in adult skeletal muscle. These results demonstrate that the skMLCK is the only tissue-specific MLCK, being expressed in adult skeletal muscle but not in cardiac, smooth, or nonmuscle tissues. In contrast, the 130-kDa smMLCK is ubiquitous in all adult tissues, including skeletal and cardiac muscle, demonstrating that, although the 130-kDa smMLCK is expressed at highest levels in smooth muscle tissues, it is not a smooth muscle-specific protein.

Abstract 1102: Cardiac-Specific Myosin Light Chain Kinase (MLCK), a Third Member of MLCK Family, Potentiates Sarcomere Formation and Cardiac Contraction

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Jason Y Chan ◽  
Morihiko Takeda ◽  
Laura E Briggs ◽  
Jonathan T Lu ◽  
Nobuo Horikoshi ◽  
...  
Keyword(s):  
Heart Failure ◽  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Cardiac Hypertrophy ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Contractile Function ◽  
Severe Heart Failure ◽  
Cardiac Contraction

Background: Two myosin light chain kinase (MLCK) proteins, skeletal (encoded by mylk2 gene) and smooth muscle MLCK (encoded by mylk1 gene) have been shown to be expressed in mammals. Human mylk2 has been mapped as a disease locus for familial cardiac hypertrophy (OMIM 606566 ), suggesting that abnormal function of skeletal MLCK stimulates cardiac hypertrophy. While phosphorylation of the putative substrate of skeletal MLCK, myosin light chain 2 (MLC2), is recognized as a key regulator of cardiac contraction, the abundance of skeletal MLCK in the heart is controversial, suggesting the existence of an additional MLCK that is preferentially expressed in cardiac muscle. Methods and Results: We characterized a new kinase named cardiac MLCK that is encoded by a gene homologous to mylk1 and 2 and is specifically expressed in the heart in both atrium and ventricle. Expression of cardiac MLCK was highly regulated by the cardiac homeobox transcription factor, Nkx2.5, in neonatal cardiomyocytes. The overall structure of cardiac MLCK protein is conserved with skeletal and smooth muscle MLCK including putative catalytic and adjacent Ca2+/calmodulin binding domains at the carboxyl-terminus. The amino-terminus is unique without significant homology to other known proteins. Cardiac MLCK phosphorylated MLC2v with a catalytic value of Km=4.3 micro M (Lineweaver-Burk analysis) indicating high affinity of cardiac MLCK to MLC2v, similar to the affinity of skeletal muscle MLCK to skeletal muscle MLC2 and smooth muscle MLCK to smooth muscle MLC2. Adenoviral-mediated overexpression of cardiac MLCK and knockdown of cardiac MLCK using RNAi in cultured cardiomyocytes revealed that cardiac MLCK regulates MLC2v phosphorylation, sarcomere organization and cardiac myocyte contraction. Expression of cardiac MLCK protein was significantly decreased in severe heart failure in vivo (post-myocardial infarction heart failure mouse model). Conclusion: Cardiac MLCK is a new key regulator of cardiac contraction and sarcomere organization. Reduction of cardiac MLCK function leading to decreased phosphorylation of MLC2v may contribute to compromised contractile function in the failing heart.

Modulator Binding Protein in Platelets

1979 ◽  
Author(s):  
L. Muszbek ◽  
J. Hàrsfalvi
Keyword(s):  
Skeletal Muscle ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Binding Protein ◽  
Troponin C ◽  
Detectable Amount ◽  
Virtual Absence ◽  
Platelet Protein ◽  
Regulator Protein

In a previous paper (Muszbek et al. FEBS Letters 1977, 80, 308) the existence of a troponin C-like protein has been revealed in platelets. This protein was isolated, characterized and identified as the multifunctional Cadependent regulator protein (modulator). Here we show that there is a platelet protein which in 6·3 M urea if Ca2+ present can form a complex with modulator protein and with skeletal muscle troponin C, too. It withstands aceton treatment and can be extracted from platelet aceton powder by 1 M KCl. Further purification could be achieved by affinity chromatography on an Affi-Gel 10-troponin C column. Modulator binding protein also copurified with platelet actomyosin though there was no detectable amount of modulator protein in this preparation. Since modulator protein appears to be responsible for the Ca2+ regulation of purified platelet myosin light chain kinase (Dabrowska and Harsthorne BBRC 1978, 85, 1352) the low Ca2+ sensitivity of platelet actomyosin may be due to the virtual absence of modulator and/or to the presence of modula tor binding prote in in thrombosthenin.

Shape and substructure of skeletal muscle myosin light chain kinase

Biochemistry ◽  
1983 ◽  
Vol 22 (18) ◽  
pp. 4316-4326 ◽  
Author(s):  
Georg W. Mayr ◽  
Ludwig M. G. Heilmeyer
Keyword(s):  
Skeletal Muscle ◽  
Light Chain ◽  
Myosin Light Chain Kinase ◽  
Myosin Light Chain ◽  
Skeletal Muscle Myosin ◽  
Muscle Myosin
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