Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q07644 (polypeptide)
 72,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mode and degree of tryptophanyl orientation relative to muscle fiber axes within hydrophobic and hydrophylic sites of myosin macromolecule in the presence of a fluorescence quencher (acrylamide, NO-3) during rigor and relaxation of glycerinated muscle fibers were studied using the polarized ultraviolet fluorescent microscopy. It was shown that myosin tryptophanyls both in LMM and HMM are oriented with their short axes along the longer axis of muscle fiber. Tryptophanyls in LMM have a more pronounced anisotropy of orientation in comparison with the fluorophore orientation anisotropy in hydrophobic sites of HMM. During the muscle fiber relaxation, conformational changes in HMM take place owing to which a section of polypeptide chain with a hydrophilic fluorophore is probably submerged deep into the macromolecule and becomes unapprochable to the quencher.
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PMID:[Polarized ultraviolet fluorescence microscopic study of the structural changes in muscle fiber contractile proteins. V. The possible nature of the conformational rearrangements in heavy meromyosin in fiber relaxation]. 36 41

A new protein component was found in heavy meromyosin and in subfragment-1 (S-1) prepared by chymotrypsin digestion of pig cardiac myosin in the presence of Ca2+. The molecular weight of this protein was estimated as 15,000 dalton. It was able to bind Ca2+ and showed a similar UV absorption spectrum to that of the g2 light chain. Heavy meromyosin and subfragment-1 which contained the 15,000 dalton component incorporated exogenous g2 and the 15,000 dalton component disappeared after such treatment. We concluded that the 15,000 dalton component was produced from g2 by limitted proteolysis. The subfragment-1 was separated into two protein fractions in equal yield by recycling the gel filtration. One contained the 15,000 dalton component and was able to bind Ca2+ while the other did not contain the component and was unable to bind Ca2+. According to analysis by SDS gel electrophoresis, the large polypeptide chain (the f component) of the first S-1 was approximately 5,000 dalton larger than the f component of the second S-1. The polypeptide corresponding to 5,000 dalton was designated polypeptide-C, because it was released from the C terminal of the f component. It seems to be essential for the attachment of the Ca2+-binding light chain g2. The location of g2 in myosin may thus be at the polypeptide-C which links the head to the tail of myosin.
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PMID:Incorporation of the Ca2+ -binding component (g2) into heavy meromyosin and subfragment-1 of pig cardiac myosin. 38 56

Ca(2+)-activated neutral proteinase was purified from rabbit skeletal muscle by a method involving DEAE-Sephacel chromatography, affinity chromatography on organomercurial-Sepharose and gel filtration on Sephacryl S-200 and Sephadex G-150. The SDS (sodium dodecyl sulphate)/polyacrylamide-gel-electrophoresis data show that the purified enzyme contains only one polypeptide chain of mol.wt. 73000. The purification procedure used allowed us to eliminate a contaminant containing two components of mol.wt. about 30000 each. Whole casein or alpha(1)-casein were hydrolysed with a maximum rate at 30 degrees C, pH7.5, and with 5mm-CaCl(2), but myofibrils were found to be a very susceptible substrate for this proteinase. This activity is associated with the destruction of the Z-discs, which is caused by the solubilization of the Z-line proteins. The activity of the proteinase in vitro is not limited to the removal of Z-line. SDS/polyacrylamide-gel electrophoresis on larger plates showed the ability of the proteinase to degrade myofibrils more extensively than previously supposed. This proteolysis resulted in the production of a 30000-dalton component as well as in various other higher- and lower-molecular-weight peptide fragments. Troponin T, troponin I, alpha-tropomyosin, some high-molecular-weight proteins (M protein, heavy chain of myosin) and three unidentified proteins are degraded. Thus the number of proteinase-sensitive regions in the myofibrils is greater than as previously reported by Dayton, Goll, Zeece, Robson & Reville [(1976) Biochemistry15, 2150-2158]. The Ca(2+)-activated neutral proteinase is not a chymotrypsin- or trypsin-like enzyme, but it reacted with all the classic thiol-proteinase inhibitors for cathepsin B, papain, bromelain and ficin. Thus the proteinase was proved to have an essential thiol group. Antipain and leupeptin are also inhibitors of the Ca(2+)-activated neutral proteinase.
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PMID:Purification and some physico-chemical and enzymic properties of a calcium ion-activated neutral proteinase from rabbit skeletal muscle. 53 1

A size class of polysomes was isolated from chick embryonic leg skeletal muscle which synthesized almost exclusively a polypeptide chain with a molecular weight identical to the myosin heavy chain. The mRNA purified from these polysomes was shown to synthesize the 200,000 dalton polypeptide in the wheat germ cell-free translation system. At least 90% of the polypeptide had properties similar to the myosin heavy chain. Isoelectric focusing indicated that the myosin heavy chain synthesized in vitro contained two chains in equal amounts, as did purified embryonic leg skeletal muscle myosin. The kinetics of hybridization of the complementary DNA with an excess of the myosin heavy chain mRNA (MHC mRNA) indicated the presence of two different mRNA sequences. Reassociation of the cDNA to an excess of the DNA of the genome suggest that there is little, if any, reiteration of the myosin heavy chain genes.
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PMID:The genes and mRNA coding for the heavy chains of chick embryonic skeletal myosin. 56 37

It has been found that a high-speed supernatant fraction from Xenopus oocytes extracted in the cold will form a clear, solid gel upon warming. Gel formation occurs within 60 min at 18 degrees-40 degrees C, and is, at least initially, temperature reversible. Gelation is strictly dependent upon the addition of sucrose to the extraction medium. When isolated in the presence of ATP, the gel consists principally of a 43,000-dalton protein which co-migrates with Xenopus skeletal muscle actin on SDS-polyacrylamide gels, and a prominent high molecular weight component of approx. 250,000 daltons. At least two minor components of intermediate molecular weight are also found associated with the gel in variable quantities. Actin has been identified as the major consituent of the gel by ultrastructural and immunological techniques, and comprises roughly 47% of protein in the complex. With time, the gel spontaneously contracts to form a small dense aggregate. Contraction requires ATP. In the absence of exogenous ATP, a polypeptide which co-migrates with the heavy chain of Xenopus skeletal muscle myosin becomes a prominent component of the gel. This polypeptide is virtually absent from gels which have contracted in ATP-containing extracts. It has also been found that Ca++ is required for gelation in oocyte extracts. At both low and high concentrations of Ca++ (defined as a ratio of Ca++/EGTA in the extraction medium), gelation is inhibited.
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PMID:Actin in Xenopus oocytes. 56 81

Brain 10 nm filaments were isolated from bovine, rabbit and rat brains by a modification of an existing procedure. The overall polypeptide composition of these preparations was similar to that previously reported for brain neurofilaments. In addition to the major polypeptide component, which has mol. wt. approx. 50 000, three other polypeptides with chain mol. wts. approx. 210 000, 155 000 and 70 000, which correspond to peripheral-nerve neurofilament polypeptides, were consistently found to be present. The mol. wt.-50 000 species was found to be heterogeneous and may contain a component derived from the mol. wt. 70 000 polypeptide. The three higher-molecular-weight polypeptides did not appear to be obviously homologous or to be homologous with myosin or Myxicola neurofilament polypeptides. These same three higher-molecular-weight components were shown to be identical with the polypeptides probably responsible for the 10 nm filaments formed during the early cycles of the tubulin-purification protocol.
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PMID:The polypeptides of isolated brain 10nm filaments and their association with polymerized tubulin. 57 9

Plasma membrane and bile canalicular membrane fractions were prepared from rat liver using NaHCO3, NaHCO3--CaCl2, and K2HPO4-KH2PO4 buffers (all at pH 7.4). The amount (expressed as milligrams protein per gram liver) of plasma membrane fraction exceeded the amount of bile canalicular membrane fraction using each of these three media; the use of NaHCO3-CaCl2 afforded a substantially higher yield of both types of membranes. The two membrane fractions exhibited complex patterns of polypeptides (greater than 30) on sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis. Several reproducible differences in polypeptide patterns were observable between the two membrane fractions; in particular, components possibly corresponding to the heavy chain of myosin and to action were prominent in the bile canalicular membrane fraction. The effects of incubation in the above three buffers and in Tris--HCl (pH 7.4) on the polypeptide patterns of both types of membrane were studied. Many polypeptides were released from each type of membrane in all of these media. Differential effects on the polypeptide patterns of either type of membrane fraction were observed among the various buffers. In terms of minimizing loss of polypeptides, in general, NaHCO3--CacCl2 appeared to be the best buffer and Tris--HCl the worst buffer. The significance of these results for the preparation and storage of liver cell plasma membrane fractions is briefly discussed.
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PMID:Studies on the preparation of rat liver plasma membrane fractions and on their polypeptide patterns. 68 61

Two polypeptides (M1 and M2) which co-sediment with F-actin in an ATP-reversible way have been detected in extracts of tissue from the rabbit visual system. Both polypeptides resemble skeletal muscle myosin in their ATP-sensitive co-sedimentation with actin, while they resemble the heavy chain of myosin and the lighter polypeptide of erythrocyte spectrin in their electrophoretic mobilities. (The estimated molecular weights are: MI congruent to 195,000; myosin congruent 200,000; M2 and spectrin congruent to 220,000). M1 and M2 were labeled in the cell bodies of the retinal ganglion cells with a radioactive amino acid and subsequently recovered in tissues (optic nerve, optic tract, lateral geniculate nucleus, and superior colliculus) containing segments of the retinal ganglion cell axons. The temporal sequence of labeling M1 and M2 in these tissues indicated that both polypeptides were synthesized in the cell bodies of retinal ganglion cells and subsequently transported down their axons at different maximum velocities. The estimated velocities were: M1, 4-8 mm per day; and M2, 2-4 mm per day.
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PMID:The identification of two intra-axonally transported polypeptides resembling myosin in some respects in the rabbit visual system. 91 92

Polyadenylylated RNA, extracted from differentiating primary cultures of rat muscle and the myogenic cell line L8, directs the synthesis of polypeptides in the wheat germ cell-free system which comigrate with myosin light chains under several electrophoretic conditions. The peptides also associate specifically with heavy myosin subunits during dissociation-reassociation treatment. Intact cells of primary skeletal muscle cultrues and of the myogenic line synthesize predominantly two ligh chains. RNA extracted from primary muscle cultures directs the synthesis of a third polypeptide in the cell-free system, similar to the third light chain found in myosin extracted from adult rat thigh muscle. Products of cell-free systems directly by RNA extracted from fibroblasts, reticulocytes, and myeloma cells did not contain detectable amounts of similar polypeptides.
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PMID:Snythesis of polypeptides with the properties of myosin light chains direct by RNA extracted from muscle cultures. 107 11

The methylation of myosin and other proteins has been studied using primary cultures of 12-day-old embryonic chick leg muscle. The methyl group of [Me-3H] methionine is incorporated into basic amino acid residues with the formation of Nepsilon-monomethyllysine, Nepsilon-dimethyllysine, Nepsilon-trimethyllysine, 3-methylhistidine, NG-monomethylarginine, and NG-dimethylarginine which are isolated from acid hydrolysates of purified myosin, and of proteins from polysomes and from the cytosol of the cultured muscle cells. In the presence of 0.1 mM cycloheximide, incorporation of [Me-3H] methionine into the polysome-bound proteins was decreased to 16.3% of control levels with no change in the pattern of incorporation into the basic amino acid residues, although protein synthesis was inhibited 97.5%. When protein synthesis was allowed to resume in such cultures by the removal of cycloheximide, polypeptides containing labeled N-methylated residues were released from polysomes into the soluble fraction. Polypeptides containing N-methylated amino acids were also released from polysomes following treatment with 2 mM puromycin. Peptidyl-tRNA, isolated from ribosomes after exposure of cultures to [Me-3H] methionine, contained labeled N-methylated amino acids. When [Me-3H] methionine was incorporated in the presence of cycloheximide, the isolated peptidyl-tRNA still contained N-methylated amino acids although the amount of methylation was 22.4% of control levels. These experiments demonstrate that N-methylation of basic amino acid residues in proteins may occur while the polypeptide is still being synthesized on the ribosome. In addition, N-methylation can occur on the nascent polypeptides in the absence of protein synthesis.
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PMID:Sites of biological methylation of proteins in cultured chick muscle cells. 110 48


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