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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this article we review the various amino acids present in vertebrate nonmuscle and smooth muscle myosin that can undergo phosphorylation. The sites for phosphorylation in the 20 kD myosin light chain include serine-19 and threonine-18 which are substrates for myosin light chain kinase and serine-1 and/or -2 and threonine-9 which are substrates for protein kinase C. The sites in vertebrate smooth muscle and nonmuscle myosin heavy chains that can be phosphorylated by protein kinase C and casein kinase II are also summarized. Original data indicating that treatment of human T-lymphocytes (Jurkat cell line) with phorbol 12-myristate 13-acetate results in phosphorylation of both the 20 kD myosin light chain as well as the 200 kD myosin heavy chain is presented. We identified the amino acids phosphorylated in the human T-lymphocytes myosin light chains as serine-1 or serine-2 and in the myosin heavy chains as serine-1917 by 1-dimensional isoelectric focusing of tryptic phosphopeptides. Untreated T-lymphocytes contain phosphate in the serine-19 residue of the myosin light chain, and in a residue tentatively identified as serine-1944 in the myosin heavy chain.
Mol Cell Biochem 1993 Nov
PMID:Phosphorylation of vertebrate nonmuscle and smooth muscle myosin heavy chains and light chains. 793 53

The goal of the current investigation was to characterize, purify, and identify the proteins that bind surfactant protein A (SP-A). Several polypeptides were purified by SP-A affinity chromatography, and the 200 kD major polypeptide that reacted with SP-A on ligand blots was purified further by preparative SDS-PAGE. Protein sequencing of proteolytically derived subfragments of this polypeptide gave sequences that corresponded completely with nonmuscle (cellular) myosin heavy chain. The 200 kD polypeptide was then found to be immunoreactive with antibodies against cellular myosin. A smaller polypeptide of 135 kD also binds SP-A and appears to be a proteolytic fragment of the 200 kD peptide. The ability of SP-A to bind myosin was confirmed in a microtiter well assay and was found to be concentration dependent. We speculated that the physiologic relevance of the interaction of SP-A with myosin might be to facilitate clearance of myosin from the alveolar subphase following its release during lung injury. In support of this hypothesis, we found that there were detectable levels of myosin in lavage fluid and that SP-A could indeed enhance uptake and degradation of myosin by alveolar macrophages.
Am J Respir Cell Mol Biol 1994 Dec
PMID:Interaction of surfactant protein A with cellular myosin. 794 98

When introduced into P19 embryonal carcinoma cells, recombinant genes encoding MyoD converted only a small percentage (< 3%) of the transfected cells into skeletal muscle. We isolated stably transfected cells that expressed the MyoD transcript. These P19[MyoD] cells continued to express markers characteristic of undifferentiated stem cells but also expressed myf-5 and the myotonic dystrophy kinase, transcripts normally present in myoblasts but absent from P19 cells. Aggregation of P19[MyoD] cells induced the expression of myogenin, desmin, and the retinoblastoma protein and resulted in the rapid and abundant development of skeletal muscle. Both the embryonic and the slow isoforms of myosin heavy chain were present in this muscle, indicating that it resembled skeletal muscle formed from primary myoblasts. Since aggregation of P19 cells normally results in inefficient differentiation and the development of only low levels of cardiac muscle but no skeletal muscle, we conclude that MyoD imposes the skeletal muscle program on P19 cells and that the differentiation of these cells requires inductive events provided by cell aggregation.
Mol Cell Biol 1994 Dec
PMID:Cellular aggregation enhances MyoD-directed skeletal myogenesis in embryonal carcinoma cells. 796 78

In plant cells, myosin is believed to be the molecular motor responsible for actin-based motility processes such as cytoplasmic streaming and directed vesicle transport. In an effort to characterize plant myosin, a cDNA encoding a myosin heavy chain was isolated from Arabidopsis thaliana. The predicted product of the MYA1 gene is 173 kDa and is structurally similar to the class V myosins. It is composed of the highly-conserved NH2-terminal "head" domain, a putative calmodulin-binding "neck" domain, an alpha-helical coiled-coil domain, and a COOH-terminal domain. Northern blot analysis shows that the Arabidopsis MYA1 gene is expressed in all the major plant tissues (flower, leaf, root, and stem). We suggest that the MYA1 myosin may be involved in a general intracellular transport process in plant cells.
J Mol Biol 1994 Jun 17
PMID:A myosin from a higher plant has structural similarities to class V myosins. 800 72

Sex-related differences in predisposition to heart diseases have long been recognized. The molecular and cellular bases for this difference are unknown. In this study we have compared expression of genes for various structural and functional proteins of muscle and interstitial compartments of the myocardium in the adult and neonatal, male and female rat heart. We have also compared cultured cardiac fibroblasts from male and female hearts with regards to gene expression and proliferative capacity. We showed that in the adult rats, the abundance of mRNAs for contractile proteins alpha- and beta-myosin heavy chain (MHC) is higher in the heart of female rats than in that of age-matched male rats. However, the difference in mRNA level for alpha-MHC was more drastic (736%, P < 0.001) than that for beta-MHC (469%, P < 0.001). mRNA levels for sarcomeric actin in the female heart were greater by 79% (P < 0.001). Collagen type I had a significantly higher (303%, P < 0.01) mRNA level in the female heart compared with the male heart. mRNAs for TGF-beta 1, cytoskeletal actin and connexin 43 were also higher (150%, P < 0.01; 130%, P < 0.01, and 150%, P < 0.01, respectively) in the female heart compared with age-matched male heart. There were no significant sex-related differences at the mRNA levels for the above proteins in ventricular tissue from neonatal male and female littermates. At the cellular level, cardiac fibroblasts obtained from adult and neonatal hearts of both sexes were comparable with respect to the abundance of mRNAs for collagen type I, TGF-beta 1 or cytoskeletal actin. However, DNA synthesis, as measured by [3H]thymidine incorporation, was higher (328%, P < 0.01) in cells from adult female heart compared with that in cells from adult male rat heart. This difference was even more pronounced in cardiac fibroblasts obtained from newborn female rats (933%, P < 0.001) compared with that in cells obtained from newborn male rat hearts. Together, these findings show that there are sex-related differences in gene expression for most major proteins in heart tissue and that this phenomenon is associated with the post-pubertal period. These findings further suggest that sex-related differential gene expression and DNA synthesis in cardiac cells are due to the regulatory effects of male- and female-specific hormones.
J Mol Cell Cardiol 1994 Feb
PMID:Gender-specific differences in expression of mRNAs for functional and structural proteins in rat ventricular myocardium. 800 87

Muscle weakness in glucocorticoid myopathy results mainly from muscle atrophy, the reason for which is the accelerated catabolism of muscle proteins. As the content of lysosomes in skeletal muscle, particularly in fast-twitch glycolytic fibers, is relatively low the non-lysosomal pathway makes a particularly significant contribution and has special importance in the initial rate-limiting steps in the catabolism of contractile proteins and in the regulation of their turnover rate. The turnover rate of actin and the myosin heavy chain is decreased in all types of muscle fibers, and more rapid turnover of the myosin light chain is registered in the fast-twitch glycolytic and oxidative-glycolytic fibers. Exercise and simultaneous glucocorticoid treatment is an effective measure in retarding skeletal muscle atrophy and provides protection against muscle wasting.
J Steroid Biochem Mol Biol 1994 Jul
PMID:Turnover of skeletal muscle contractile proteins in glucocorticoid myopathy. 804 26

The myocardium is a highly adaptive tissue, as evidenced by phenotypic alterations throughout development and under conditions of altered hemodynamic load. With pressure overload, the myocardium displays adult-to-fetal transitions in expression of contractile and non-contractile proteins. Most intriguing is the fact that many of these transitions are also observed in the senescent heart. The purpose of this work was to establish if the thin filament regulatory proteins, troponin I and troponin T, exhibit reexpression of early developmental isoforms, suggestive of coordinate reprogramming of contractile protein isoform expression. As a functional index of reexpression of the early isoform of troponin I, slow skeletal troponin I, myofibrils were isolated from 12 and 24-month-old Fischer 344 rat ventricles and assayed for myofibrillar ATPase activity at pH 7.0 and 6.5. Both preparations displayed rightward shifts in Ca-ATPase relationships with no differences between groups. SDS-PAGE and Western blot analysis showed that whereas myosin heavy chain expression underwent a transition to predominance of the early development isoform, beta-myosin heavy chain, there was no reexpression of the fetal isoforms of either troponin I or troponin T in the rat heart at 24 months of age. Northern blot analysis using cDNA probes specific for cardiac or slow skeletal troponin I also confirmed the lack of slow skeletal reexpression in the 24-month ventricle. These results are significant in that they demonstrate a lack of coordinate expression of contractile protein isoforms under myocardial adaptation to the aging process.
J Mol Cell Cardiol 1994 Apr
PMID:Discoordinate regulation of contractile protein gene expression in the senescent rat myocardium. 807 7

In myocardium from different rat models of cardiac hypertrophy, expression of Na+,K(+)-ATPase isoforms has been shown to be altered at the mRNA level. However, it has not been determined whether these alterations translate into changes at the protein level. This distinction is important because post-transcriptional events have been shown to regulate isoform expression. In the present study, relative abundances of the Na+,K(+)-ATPase isoforms were examined in hypertrophied left ventricles of renovascular hypertensive rats at both the protein and mRNA levels, using immunoblotting and dot blot hybridization, respectively. Stenosis of the left renal artery elicited an increase in systolic blood pressure, cardiac hypertrophy, and a shift in expression of the myosin heavy chain isoforms. In hypertrophied left ventricles, expression of the alpha 1 isoform remained unchanged at both mRNA and protein levels, whereas the relative abundances of both alpha 2-mRNA and -protein decreased, to 0.63 and 0.54, respectively, of controls. In addition, the abundance of beta 1-mRNA remained unchanged, whereas beta 1-protein decreased to 0.67 of controls. These results suggest that in hypertrophied myocardium of renovascular hypertensive rats Na+,K(+)-ATPase isoform expression is altered at both the protein and mRNA levels, and that pretranslational as well as translational/post-translational mechanisms may be involved.
J Mol Cell Cardiol 1994 May
PMID:Cardiac hypertrophy alters expression of Na+,K(+)-ATPase subunit isoforms at mRNA and protein levels in rat myocardium. 807 13

We have determined the molecular lesion in Mhc9, a homozygous-viable mutant of the Drosophila muscle myosin heavy chain gene. This mutation is in an adult-specific alternative exon (exon 9a) which encodes a portion of the myosin head that is highly conserved among both cytoplasmic and muscle myosins of all organisms. The mutation results in a charge change in the evolutionarily invariant amino acid residue 482. The phenotype of the homozygous mutant is identical to that of an organism having a stop codon within alternative exon 9a, i.e. lack of thick filaments in the indirect flight muscles and a greatly reduced number of thick filaments in the small cells of the jump muscles. This phenotype correlates with the known expression pattern of exon 9a. Genetic, biochemical and ultrastructural analyses show that the failure to accumulate thick filaments in the mutant is not a result of aberrant interactions with thin filaments and that the mutant myosin heavy chain does not poison assembly of wild-type thick filaments. Our results, in conjunction with recent structural and mutant studies by others, indicate that residue 482 is important for generating ATPase activity and for myosin stability in muscle.
J Mol Biol 1994 Feb 25
PMID:A charge change in an evolutionarily-conserved region of the myosin globular head prevents myosin and thick filament accumulation in Drosophila. 811 87

Based on previous immunological data, cross-reactivity of myosin heavy chain (MHC) with the ventricular (V) isoform was observed in primordia of avian skeletal muscles and in regenerating adult anterior latissimus dorsi (ALD) muscle. To determine whether this primordial (P) MHC is identical to adult V-MHC gene product, we have cloned and characterized the 3' portion of MHC cDNA that is expressed in ALD muscle at 3 d of regeneration. Comparison of nucleotide sequences between adult V-MHC and P-MHC cDNAs revealed more than 98% homology in the 3'-untranslated (UT) portions of these genes. The expression pattern of P-MHC was analyzed in adult regenerating muscles using total RNA from two fast muscles, posterior latissimus dorsi (PLD) and pectoralis major (PM), as well as from slow ALD and mixed fast/slow gastrocnemius muscles at 0, 1, 3, 4, 6, 9, and 14 d after cold injury. Identical results were obtained by RNase protection assays using either a probe specifying the coding region of adult V-MHC or a P-MHC probe encoding the carboxy end plus the 3'-UT region. The expected protected fragments were detected early from day 2 up to day 6 in ALD muscle. Similar rate of appearance, reaching the highest level at day 3, was observed in PLD, PM, and gastrocnemius muscles. However, the amount and the kinetics of disappearance differed among the various muscles analyzed. In contrast, during development, steady-state levels and kinetics of V-MHC mRNA expression were found to be alike in axial and appendicular muscles. These data strongly suggest the identity of P-MHC as the ventricular isoform and support the concept that expression of P-MHC mRNA is a common feature of developing as well as of all regenerating adult skeletal muscles. Interestingly, no expression of cardiac specific myosin light chain (MLC) 2A was observed after cold injury, suggesting independent regulatory pathways for the two kinds of myosin subunits.
Cell Mol Biol Res 1993
PMID:Differential expression of ventricular-like myosin heavy chain mRNA in developing and regenerating avian skeletal muscles. 817 88


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