Phosphorylation <i>in vivo</i> of the P light chain of myosin in rabbit fast and slow skeletal muscles

Westwood, Sara A.; Hudlická, O; Perry, S. V.

doi:10.1042/bj2180841

Cited by 33 publications

(24 citation statements)

References 19 publications

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“…They were designated as LC-2, LC2*, LC-2P (the phosphorylated form of LC-2), and LC-2*P (the phosphorylated form of LC-2*), following the nomenclature of Price et al 31 We observed two phosphorylatable P-LC in the ventricle but only one phosphorylatable P-LC in the atrium of human and pig even after preincubation of skinned fibers with MLCK. This observation is in agreement with the concept of Westwood et al, 35 who showed that a P-LC polymorphism exists in slow but not in fast muscle of mammalia as the atrium of human and pig showed a higher shortening velocity than the ventricle. In contrast, Price et al 31 observed two phosphorylatable P-LC in the human atrium.…”

Section: Figure 3 Characterization Of the Myosin P Light Chain Of Thsupporting

confidence: 82%

Skinned fibers of human atrium and ventricle: myosin isoenzymes and contractility.

Morano

Arndt

Gärtner

et al. 1988

Circulation Research

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Different myosin isoenzymes of pig and human atrium and ventricle and rat ventricle were characterized by two approaches: pyrophosphate polyacrylamide gel electrophoresis (PP-PAGE) and analysis of the myosin P light chains by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). We further investigated the relation between atrial and ventricular myosin isoenzymes of human, pig, and rat, and the maximum (unloaded) shortening velocity ( V J and the Ca 2+ sensitivity of chemically skinned fibers of the same species. The myosin isoenzymes of both human and pig atrium comigrated in the PP-PAGE with rat V 2 isomyosin, whereas the ventricle of human and pig comigrated with rat V,. In both human and pig ventricle, a myosin P light chain polymorphism exists (two phosphorylatable P light chains with the same molecular weight but different isoelectric points). In contrast, we found no P light chain polymorphism in the atrium of human and pig and in the ventricle of rat (one phosphorylatable P light chain only). A correlation exists between V.^, Ca 2+ sensitivity, and atrium-and ventricle-specific myosin isoenzymes of human and pig. V M< was determined by the slack-test method. Plots of Al versus At of atrial and ventricular skinned fibers were well fitted by a single straight line up to Al = 15% and Al = 13%, respectively. V^ of skinned ventricular fibers was lower than V.,., of skinned atrial fibers in both human and pig. Ca J+ sensitivity of skinned fibers of ventricle, however, was higher than Ca 2+ sensitivity of atrial skinned fibers in both human and pig.

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Section: Figure 3 Characterization Of the Myosin P Light Chain Of Thsupporting

confidence: 82%

Skinned fibers of human atrium and ventricle: myosin isoenzymes and contractility.

Morano

Arndt

Gärtner

et al. 1988

Circulation Research

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“…With respect to phosphorylation of P light chain isolated from rabbit soleus muscle, these results are dissimilar to those reported by Westwood et al (1984). They found that fused tetanic contraction of rabbit soleus muscle resulted in a large increase in the phosphate content of two forms of P light chain.…”

Section: Westwood Et Al (1984)contrasting

confidence: 82%

“…As a consequence, the high basal value of 0.5 mol phosphate/mol P light chain reported by Stull and High (1977) was probably an artifact of the precontraction. Westwood et al (1984) also reported a basal P light chain phosphate content of 0.50 mol phosphate/mol P light chain in combined frozen samples of rabbit tibialis anterior and extensor digitorum longus muscles. The reason for this elevated basal value may have been due to slow freezing of large 3-5-g biopsy samples.…”

Section: Discussionmentioning

confidence: 92%

Phosphorylation of rabbit skeletal muscle myosin in situ

Moore

Houston

Iwamoto

et al. 1985

Journal Cellular Physiology

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Myosin light chain (P light chain) is phosphorylated by Ca2+ X calmodulin-dependent myosin light chain kinase. Based on studies with rat skeletal muscles, it has been shown that P light chain phosphorylation correlated to the extent of potentiation of isometric twitch tension. It is not clear whether this correlation exists in rabbit skeletal muscle, which has been the primary source of contractile proteins for biochemical studies. Therefore, phosphorylation of myosin P light chain in rabbit slow-twitch soleus and fast-twitch plantaris muscles in situ was examined. Electrical stimulation (5 Hz, 20 seconds) of plantaris muscle produced an increase in the phosphate content of P light chain from 0.17 to 0.45 mol phosphate/mol P light chain. This increase in phosphate content was accompanied by a 58% increase in maximal isometric twitch tension. Tetanic stimulation (100 Hz, 15 seconds) of rabbit soleus muscle resulted in only a small increase in P light chain phosphate content from 0.02 to 0.10 mol phosphate/mol P light chain, and posttetanic twitch tension did not increase significantly. The correlation between potentiated isometric twitch tension and P light chain phosphorylation in rabbit fast-twitch muscle is similar to that observed in rat skeletal muscle. These results were consistent with the hypothesis that phosphorylation of rabbit skeletal muscle myosin, which results in an increase in actin-activated ATPase activity, may be related to isometric twitch potentiation.

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“…a pair of essential light chains (MELC) and a pair of regulatory (phosphorylatable) light chains (MRLC) [l]. Phosphorylation of MRLC by Ca2 +-calmodulin-dependent myosin light chain kinase (MLCK) is considered in smooth muscle and nonmuscle cells to be a trigger event initiating the interaction of myosin with actin [2, 31. Only a single isoform of MRLC was detected in rabbit fast-twitch skeletal muscle in two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) under dephosphorylated condition [4]. In contrast, two isoelectric variants of cardiac (or slow-twitch skeletal) MRLC have been reported in mammals [5] and in the chicken [6].…”

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confidence: 99%

Two isoforms of smooth muscle myosin regulatory light chain in chicken gizzard

Inoue

Yanagisawa

Takano‐Ohmuro

et al. 1989

European Journal of Biochemistry

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We isolated a cDNA clone for a new isoform of chicken smooth muscle myosin regulatory light chain (MRLC) from a cDNA library of embryonic chicken gizzard. The deduced amino acid sequence was different in 10 amino acid residues from the previously reported polypeptide sequences of chicken gizzard MRLC. The in vitro transcription/translation product from the cDNA comigrated with a minor isoform of chicken gizzard MRLC (L,,-B) in a two-dimensional gel electrophoresis. This isoform was detected only in the embryonic gizzard and was slightly more acidic than the predominant isoform (L20-A). The partial polypeptide sequence of L20-A was confirmed to be identical to the previously reported MRLC sequence. Nevertheless, Northern blot analysis showed that Lzo-B-related mRNAs were present in both the embryonic and adult gizzard. Non-denaturing pyrophosphate polyacrylamide gel electrophoresis showed that the in vitro transcription/translation product could be associated with native myosin when mixed and coprecipitated in a low-ionic-strength buffer with adult chicken gizzard myosin. Moreover, the coprecipitated translation product was phosphorylated in vitro by chicken gizzard myosin light chain kinase apparently more rapidly than LI0-A on the native myosin heavy chain. From these findings, we concluded that at least two isoforms of smooth muscle MRLC exist in chicken gizzard and that their expression may be regulated translationally depending on the developmental stage.

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Phosphorylation in vivo of the P light chain of myosin in rabbit fast and slow skeletal muscles

Cited by 33 publications

References 19 publications

Skinned fibers of human atrium and ventricle: myosin isoenzymes and contractility.

Skinned fibers of human atrium and ventricle: myosin isoenzymes and contractility.

Phosphorylation of rabbit skeletal muscle myosin in situ

Two isoforms of smooth muscle myosin regulatory light chain in chicken gizzard

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