Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0272170 (SDS)
 50,377 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A myosin B-like protein was extracted from the alga Nitella flexilis. SDS-polyacrylamide gel electrophoresis revealed the presence of myosin heavy chain and actin as the main components. At high ionic strength, its ATPase [EC 3.6.1.3] reaction was activated by EDTA or Ca2+ and inhibited by Mg2+. At low ionic strength, superprecipitation was induced by the addition of ATP. Myosin was purified from Nitella myosin B. The molecular weight of the heavy chain of Nitella myosin, estimated by SDS-gel electrophoresis, was slightly higher than that of skeletal muscle myosin. At low ionic strength, Nitella myosin aggregated to form bipolar filaments about 0.2 micron long. At high ionic strength, its ATPase reaction was activated by EDTA or Ca2+, and inhibited by Mg2+. The Mg2+-ATPase reaction of Nitella myosin was activated by skeletal muscle F-actin.
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PMID:Identification of myosin in Nitella flexilis. 14 21

Proteins of apparent molecular weights between 10 000 and 250 000 could be solubilized from guinea pig epidermis using a Tris/sucrose/ATP buffer. When the ionic concentration of the solubilized extract was made 75 mM with respect to KCl and 2 mM with respect to MgCl2, a protein complex precipitated which on SDS-polyacrylamide gel electrophoresis resolved into bands corresponding in migration to myosin, actin and a number of low molecular weight proteins. Myosin was dissociated from the complex with 0.6 M KI and purified by gel filtration chromatography on an agarose column. The purified epidermal myosin fraction contained a polypeptide of 200 000 molecular weight andtwo low molecular weight polypeptides of 16 500 and 13 000. The amino acid composition of the epidermal myosin heavy chain was similar to that of muscle myosin. At high ionic strength epidermal myosin had high specific (K+ + Ca2+)- and (K+ + EDTA)-ATPase activities and low specific (K+ + Mg2+)-ATPase activity. The pH activity curves of the (K+ + Ca2+)- and (K+ + EDTA)-ATPase were different. ATP was hydrolyzed faster than other nucleoside triphosphates. At low ionic strength, the (K+ + Mg2+)-ATPase activity of epidermal myosin was stimulated two fold by skeletal muscle actin. The myosin formed bipolar filaments in 50 mM KCl in the presence of 5 mM Mg2+.
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PMID:Contractile proteins in epidermis. Isolation and properties of guinea-pig epidermal myosin. 22 13

Recessive mutant gene c in Ambystoma mexicanum embryos causes a failure of the heart to function even though initial heart development appears normal. An analysis of the constituent proteins of normal and mutant hearts by SDS-poly-acrylamide gel electrophoresis shows that actin (43,000 daltons) is present in almost normal amounts, while myosin heavy chain (200,000 daltons) is somewhat reduced in mutants. Both SDS-polyacrylamide gel electrophoresis and immunofluorescence studies reveal that tropomyosin is abundant in normal hearts, but very much reduced in mutants. Electron microscope studies of normal hearts show numerous well-organized myofibrils. Although mutant cardiomyocytes contain a few 60- and 150-A filaments, organized sacromeres are absent. Instead, amorphous proteinaceous collections are prominent. Previously reported heavy meromyosin (HMM)-binding experiments on glycerinated hearts demonstrate that most of the actin is contained within the amorphous collections in a nonfilamentous state, and the addition of HMM causes polymerization into F actin (Lemanski et al., 1976, J. Cell. Biol. 68:375-388). In the present study, glycerol-extracted hearts are incubated with tropomyosin, purified from rabbit or chicken skeletal muscle. This treatment causes the amorphous collections to disappear, and large numbers of distinct thin actin (60- to 80-A) filaments are seen in their place. Negative staining experiments corroborate this observation. These results suggest that the nonfilamentous actin located in the amorphous collections of mutant heart cells is induced to form into filaments with the addition of tropomyosin.
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PMID:Role of tropomyosin in actin filament formation in embryonic salamander heart cells. 38 24

The 3-dimensional structure of the fibrous cytoskeleton of 3T3 cells was examined by scanning electron microscopy of cells extracted with the non-ionic detergent Triton X-100. Detergent-extracted cells consist of the nucleus and an extensive system of fibres, the largest of which correspond to stress fibres visible by phase-contrast microscopy. The system of fibres, which is coterminous with the borders of the native cell, remains firmly adherent to the substratum. The major fibres branch into smaller fibrils which appear to end by ravelling out into fine filaments that constitute a matted network in a plane very close to that of the substratum. In the nuclear region all the major fibres pass over the top of the nucleus, where they may also branch into a system of fine fibrils. Thin-section transmission electron microscopy in conjunction with heavy meromyosin treatment of extracted cells shows the fibres to be composed of native F-actin. Intermediate filaments are also present, and are prominent in the matted network, together with actin filaments. The major proteins of the residue are identified by SDS-polyacrylamide gel electrophoresis as actin, a 56000 Dalton peptide, and histones. Also present are myosin heavy chain, peptides of 225,000 and 250,000, and minor bands at 60,000 and 94,000 Daltons. The non-ionic detergent extracts 70% of the cellular protein, including 50% of the actin and 75% of the myosin. The Triton-insoluble fraction of 3T3 cells appears to constitute, in addition to the nucleus, a stable cytoskeletal system, composed largely of contractile proteins and 10-nm filaments, which functions in maintenance of cell shape, in substratum adhesion, and in positioning the nucleus within the cell.
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PMID:Intracellular fibres in cultured cells: analysis by scanning and transmission electron microscopy and by SDS-polyacrylamide gel electrophoresis. 56 65

The effect of homozygosity for recessive gene c in Ambystoma mexicanum is the absence of a heartbeat even though initially heart development appears normal. Mutant embryos (c/c) are first distinguishable from their normal siblings (+/+;+/c) at stage 34 (7 days after fertilization) when the normals develop contracting hearts. The mutant hearts at this stage, upon gross examination, appear structurally normal but fail to beat. Nevertheless, the mutants survive through stage 41, which is about 20 days beyond the heartbeat stage, and they exhibit normal swimming movements, indicating that gene c does not affect skeletal muscle. Electron microscopic studies of normal hearts show some myofibrils to be present at stage 34; by stage 41, the normal myocardial cells have become highly differentiated muscle cells. Although some mutant heart cells contain a few thin 60 A and thick 150 A filaments, organized myofibrils are absent. Instead, amorphous proteinaceous collections are prominent. Heavy meromyosin (HMM) binding experiments were performed on mutant hearts to determine whether the myocardial cells contain actin. Mutant myocardial cells that are glycerinated but not treated with HMM contain intact amorphous bodies. After incubation in HMM, the amorphous collections are no longer present and large numbers of decorated actin filaments appear. The.results suggest that the amorphous proteinaceous collections contain actin in a nonfilamentous form, and the addition of HMM induces this actin to polymerize into filaments. SDS-polyacrylamide gel electrophoresis of mutant heart tissue supports this conclusion by showing a prominent 43,000 dalton band suggestive of actin. The electrophoresis experiments also demonstrate a significant reduction of myosin heavy chain (200,000 daltons) in mutant hearts when compared to normal, and this latter observation is confirmed by radioimmunoassay experiments. Muscle tropomyosin (34,000 daltons), prominent in normal hearts, is virtually nonexistent in mutants. Thus, it appears that this single gene mutation affects the accumulation and organization of several different muscle proteins, including actin, myosin, and tropomyosin.
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PMID:Morphological and biochemical abnormalities in hearts of cardiac mutant salamanders (Ambystoma mexicanum). 103 76

Cardiac myosin heavy chain expression undergoes a perinatal transition from predominance of beta-MHC to alpha-MHC. In the current study, we tested the effects of glucocorticoids in this early transition period, by treating pregnant rats with dexamethasone on gestational days 17, 18 and 19, using doses below (0.05 mg/kg), at (0.2 mg/kg) or above (0.8 mg/kg) the threshold for growth retardation. Cardiac MHC isoforms were resolved with a denaturing SDS-PAGE system, followed by quantitative densitometry. In normal animals alpha-MHC was only 10% of the total on gestational day 18 but rose to 35% by postnatal day 1, and to 95% by the end of the first month postpartum. During the early phase of this transition, the lowest dose of dexamethasone significantly promoted alpha-MHC expression without inhibiting body or heart growth; regression analysis indicated a 40% increase in the slope of MHC isoform transition with respect to tissue weight. In contrast, the higher, growth-retarding doses of dexamethasone either failed to enhance alpha-MHC expression or caused biphasic changes, with inhibition at ages corresponding to the onset of weight deficits; regression analysis indicated that the effects of the higher doses on MHC could all be accounted for by changes in tissue weight. Glucocorticoid levels rise substantially in the period surrounding parturition, and serve to program the development and coupling of adenylate cyclase to membrane receptors; because adenylate cyclase has been shown to elicit the beta-MHC to alpha-MHC transition in vitro, our results suggest that glucocorticoids, along with thyroid hormone and beta-adrenergic stimulation, influence the ontogenetic program of MHC isoform transition.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Glucocorticoids accelerate the ontogenetic transition of cardiac ventricular myosin heavy-chain isoform expression in the rat: promotion by prenatal exposure to a low dose of dexamethasone. 128 77

Cardiac myosin heavy chain (MHC) expression undergoes an ontogenetic transition from beta to alpha MHC isoforms. Although thyroid hormone plays a role in this change, the timing of the events suggests the participation of other factors. Using a new, denaturing SDS-PAGE procedure that cleanly resolves the beta and alpha heavy chains, we have assessed the role of beta-adrenergic stimulation on this transition in fetal and neonatal rat hearts. In control animals at embryonic day 20, less than 15% of the MHC was the alpha-form, and the proportion increased to approximately 35% by postnatal day 1 and to 80% by postnatal day 8. Although catecholamine levels rise abruptly at birth, and cyclic AMP levels increase the expression of alpha-MHC in vitro, neither premature beta-adrenergic stimulation (maternal treatment with terbutaline on embryonic days 17, 18 and 19) nor continuous prenatal blockade of beta-receptors (maternal propranolol infusions from embryonic day 7 onward) influenced the developmental profile. Because beta-receptors in fetal and neonatal heart are functionally linked to adenylate cyclase, and cyclic AMP has been shown to promote the expression of alpha-MHC, the lack of effect of terbutaline or propranolol suggests that activation of adenylate cyclase through fetal cardiac beta-receptors is not sufficient to mediate the switchover without participation of other factors, such as thyroid or steroid hormones, or hypoxia.
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PMID:Ontogenetic transition of cardiac myosin heavy chain isoforms in rat ventricle: effects of fetal exposure to beta-adrenergic agonists or antagonists. 135 26

The cilium of a vertebrate photoreceptor cell connects the phototransductive outer segment of the cell to the inner segment. Previous studies have shown that, within the connecting cilium, there is a small cluster of actin filaments, which play a critical role in the formation of new disk membranes. Here, we have detected a polypeptide in rat rod outer segments that is recognized by myosin heavy chain antibodies and was found to possess other characteristics of conventional non-muscle myosin heavy chain: it comigrates in SDS-PAGE with non-muscle myosin heavy chain; it associates with the cytoskeleton of rod outer segments in an ATP-sensitive manner; and it binds to purified actin filaments in the absence of ATP. Myosin ATPase activity was also detected in isolated rod outer segments. Electron immunomicroscopy revealed that myosin is present in the small actin-containing domain within the connecting cilium at the site of disk membrane morphogenesis. These results pose the possibility that an actin-myosin contractile mechanism functions in the formation of new photoreceptor disk membranes.
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PMID:Association of myosin with the connecting cilium of rod photoreceptors. 142 4

Fish species of seafood made of washed fish flesh (e.g. imitation crab meat from surimi) were identified by peptide mapping of the myosin heavy chain (MHC). In the first step the MHC was separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in 7.5% T gel, followed by a second SDS-PAGE in a 15% T gel with proteolytic digestion of the MHC in the gel. The resulting peptides gave species specific patterns.
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PMID:Fish species identification by peptide mapping of the myosin heavy chain. 145 17

The labeling of muscle fiber proteins with iodoacetamido)tetramethylrhodamine (IATR) was reinvestigated with the purified 5' or 6' isomers of IATR. Both isomers modify the myosin heavy chain within the 20-kDa fragment of myosin subfragment 1 (S1) but with different rates, and only the 5'-IATR alters K(+)-EDTA- and Ca(2+)-activated ATPases. Absorption spectroscopic and ATPase studies of probe stoichiometry indicate that for 5'-IATR there are two probes per myosin sulfhydryl 1 (SH1). Quantitative fluorograms of the SDS-PAGE gels confirm that there are one covalent and one noncovalent probe per SH1 when S1 is labeled with 5'-IATR (5'-IATR-S1) and that there are one covalent and two noncovalent probes per S1 when S1 is labeled with 6'-IATR (6'-IATR-S1). The 5'- and 6'-IATR probes have similar fluorescent lifetimes when bound to S1, but quenching studies with potassium iodide show that 5'-IATR-S1 has a single class of strongly bound chromophores while 6'-IATR-S1 has two or more classes of chromophores. It is possible that 5'-IATR labels SH1 as a dimer. The polarization anisotropies of 5'- and 6'-IATR-S1 indicate that 5'-IATR is immobilized, while 6'-IATR is moving independently, on the surface of S1. The emission spectrum from 5'-IATR-S1 is unaffected by the addition of MgATP, while 6'-IATR-S1 shows a spectral shift and total intensity change. When labeling muscle fibers, 5'-IATR labels myosin SH1 and differentiates between the fiber physiological states by indicating cross-bridge rotation in quantitative agreement with previous results [Burghardt et al. (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 7515]. 6'-IATR reacts preferentially with actin in muscle fibers and does not differentiate between fiber physiological states as expected for an actin probe. The stereospecificity of the rhodamine isomers for SH1 indicates features of the local protein structure. The experimental results are used with theoretical methods for determining molecular structure to suggest a qualitative scheme for the specific interaction of 5'-IATR with its binding pocket on the surface of S1.
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PMID:Stereospecific reaction of muscle fiber proteins with the 5' or 6' isomer of (iodoacetamido)tetramethylrhodamine. 146 29


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