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)

Dictyostelium cells, devoid of conventional myosin, display a variety of motile activities, consistent with the presence of other molecular motors. The Dictyostelium genome was probed at low stringency with a gene fragment containing the conserved conventional myosin head domain sequences to identify other actin-based motors that may play a role in the observed motility of these mutant cells. One gene (abmA) has been characterized and encodes a polypeptide of approximately 135 kDa with a head region homologous to other myosin head sequences and a tail region that is not predicted to form either an alpha-helical structure of coiled-coil interactions. Comparisons of the amino acid sequences of the tail regions of abmA, Dictyostelium myosin I, and Acanthamoeba myosins IB and IL reveal an area of sequence similarity in the amino terminal half of the tail that may be a membrane-binding domain. The abmA gene, however, does not contain an unusual Gly, Pro, Ala stretch typical of many of the previously described myosin Is. Two additional genes (abmB and abmC) were identified using this approach and also found to contain sequences that encode proteins with typical conserved myosin head sequences. The abm genes may be part of a large family of actin-based motors that play various roles in diverse aspects of cellular motility.
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PMID:Multiple actin-based motor genes in Dictyostelium. 251 18

Antisera to microtubule-enriched fraction from normal human brain (anti-MT sera) label neurofibrillary tangles and neurites of neuritic (senile) plaques in brain sections of cases with Alzheimer disease/senile dementia of the Alzheimer type (AD/SDAT); the plaque core amyloid is not labeled. These anti-MT sera label both tangles in tissue sections and smears of isolated tangles which had been extracted with sodium dodecyl sulfate (SDS) to remove impurities trapped in between the paired helical filaments (PHF). The tangle labeling of anti-MT sera is eliminated on their absorption both with microtubule-enriched fractions from human and animal brain and with the isolated PHF. Neurofilament triplet, actin, myosin, keratin, or fibroblasts do not absorb the tangles staining antibodies. Furthermore, antisera containing antibodies to tubulin, microtubule-associated high mol. wt. polypeptides (MAPS), neurofilament triplet, and the 50,000 mol. wt. contaminant of CNS neurofilament preparations do not label tangles. On immunoblots of SDS-polyacrylamide gels of isolated PHF anti-MT sera label some of the same polypeptides identified with antisera to PHF; affinity-purified antibodies to tubulin used as a control do not label any PHF polypeptide on the immunoblots. The anti-MT sera, when preabsorbed with the PHF polypeptides eluted from SDS-polyacrylamide gels, do not label tangles. These studies demonstrate that a polypeptide/s cross-reactive with Alzheimer PHF is indeed normally present in brain and that it is different from tubulin, neurofilament triplet, actin, myosin, vimentin, and keratin.
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PMID:Alzheimer paired helical filaments: cross-reacting polypeptide/s normally present in brain. 258 15

The pathogenesis of reduced systolic left ventricular function in dilated cardiomyopathy is yet unclear. To analyze a possible involvement of contractile protein, function and structure of left ventricular myofibrils were examined in hearts of patients with advanced cardiomyopathy undergoing heart transplantation and in normal control hearts (from renal transplant donors). Myosin and actin content of the left ventricular myocardium was slightly reduced in cardiomyopathic hearts. Myofibrillar polypeptide composition was determined using two-dimensional electrophoresis and immunoblotting. No differences in constituting polypeptides were apparent, including Z-line proteins and proteins of the endosarcomeric lattice. M-line-bound creatine kinase was identical in both groups. Further, basal and maximal myofibrillar adenosine triphosphatase (ATPase) activities were unaltered in dilated cardiomyopathy. The structure of purified myosin was identical in both groups by the following criteria: electrophoretic mobility of native myosin, identical pattern of light chains after isoelectric focusing, identical cleavage peptides of myosin's heavy chain, and identical patterns after immunoblotting of heavy chain cleavage peptides using polyclonal antibodies generated against myosin from normal and cardiomyopathic ventricles. Ca2+-activated, K+-EDTA-activated and actin-activated myosin ATPase activities were identical in control and cardiomyopathic hearts. A structural alteration or functional defect of myofibrils does not seem to be primarily involved in the pathogenesis of reduced myocardial contractility in dilated cardiomyopathy.
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PMID:Structure and function of contractile proteins in human dilated cardiomyopathy. 258 58

Exposure of skeletal myoblasts to growth factor-deficient medium results in transcriptional activation of muscle-specific genes, including the muscle creatine kinase gene (mck). Tissue specificity, developmental regulation, and high-level expression of mck are conferred primarily by a muscle-specific enhancer located between base pairs (bp) -1350 and -1048 relative to the transcription initiation site (E. A. Sternberg, G. Spizz, W. M. Perry, D. Vizard, T. Weil, and E. N. Olson, Mol. Cell. Biol. 8:2896-2909, 1988). To begin to define the regulatory mechanisms that mediate the selective activation of the mck enhancer in differentiating muscle cells, we have further delimited the boundaries of this enhancer and analyzed its interactions with nuclear factors from a variety of myogenic and nonmyogenic cell types. Deletion mutagenesis showed that the region between 1,204 and 1,095 bp upstream of mck functions as a weak muscle-specific enhancer that is dependent on an adjacent enhancer element for strong activity. This adjacent activating element does not exhibit enhancer activity in single copy but acts as a strong enhancer when multimerized. Gel retardation assays combined with DNase I footprinting and diethyl pyrocarbonate interference showed that a nuclear factor from differentiated C2 myotubes and BC3H1 myocytes recognized a conserved A + T-rich sequence within the peripheral activating region. This myocyte-specific enhancer-binding factor, designated MEF-2, was undetectable in nuclear extracts from C2 or BC3H1 myoblasts or several nonmyogenic cell lines. MEF-2 was first detectable within 2 h after exposure of myoblasts to mitogen-deficient medium and increased in abundance for 24 to 48 h thereafter. The appearance of MEF-2 required ongoing protein synthesis and was prevented by fibroblast growth factor and type beta transforming growth factor, which block the induction of muscle-specific genes. A myoblast-specific factor that is down regulated within 4 h after removal of growth factors was also found to bind to the MEF-2 recognition site. A 10-bp sequence, which was shown by DNase I footprinting and diethyl pyrocarbonate interference to interact directly with MEF-2, was identified within the rat and human mck enhancers, the rat myosin light-chain (mlc)-1/3 enhancer, and the chicken cardiac mlc-2A promoter. Oligomers corresponding to the region of the mlc-1/3 enhancer, which encompasses this conserved sequence, bound MEF-2 and competed for its binding to the mck enhancer. These results thus provide evidence for a novel myocyte-specific enhancer-binding factor, MEF-2, that is expressed early in the differentiation program and is suppressed by specific polypeptide growth factors. The ability of MEF-2 to recognize conserved activating elements associated with multiple-specific genes suggests that this factor may participate in the coordinate regulation of genes during myogenesis.
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PMID:A new myocyte-specific enhancer-binding factor that recognizes a conserved element associated with multiple muscle-specific genes. 260 7

Using a complementary sequence or antipeptide to selectively neutralize the stretch of residues 633-642 of skeletal myosin heavy chain, we recently demonstrated that this segment is an actin binding site operating in the absence as in the presence of nucleotide and that this stretch 633-642 is not part of the nucleotide binding site [Chaussepied & Morales (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 7471-7475]. In the present study, we determined that the covalent cross-linking of the antipeptide to the stretch 633-642 [induced by 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide] does not alter the overall polypeptide conformation since no changes were observed on the far-ultraviolet CD spectra and thiol reactivity measurements. The presence of the antipeptide did not influence significantly the enhancement of tryptophan fluorescence induced by ATP.Mg2+ or ADP.Mg2+ binding to the myosin head (S1) nor did it on the ATP.Mg2+-induced tryptic proteolysis of S1 heavy chain. Moreover, fluorescence quenching studies, using acrylamide and the analogue, 1,N6-ethenoadenosine 5'-triphosphate, indicated that the nucleotide bound to antipeptide-S1 complex has an accessibility to the solute quencher close to that observed when it is bound to native S1. Additionally, neutralization of the stretch 633-642 of the S1 heavy chain by the antipeptide did not influence the stabilization of the Mg2+.ADP.sodium vanadate-S1 complex. On the other hand, experiments using antipeptide-induced protection against the cleavage of the S1 heavy chain by Arg-C protease demonstrated that the presence of Mg2+.ADP.sodium vanadate in the S1 nucleotide site did not affect the interaction of the antipeptide with the stretch of residues 633-642.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Interaction between stretch of residues 633-642 (actin binding site) and nucleotide binding site on skeletal myosin subfragment 1 heavy chain. 260 45

A myosin heavy chain polypeptide has been identified and localized in Nicotiana pollen tubes using monoclonal anti-myosin antibodies. The epitopes of these antibodies were found to reside on the myosin heavy chain head and rod portion and were, therefore, designated anti-S-1 (myosin S-1) and anti-LMM (light meromyosin). On Western blots of the total soluble pollen tube proteins, both anti-S-1 and anti-LMM label a polypeptide of approximately 175,000 Mr. Immunofluorescence microscopy shows that both antibodies yield numerous fluorescent spots throughout the whole length of the tube, often with an enrichment in the tube tip. These fluorescent spots are thought to represent vesicles and/or organelles in the pollen tubes. In addition to this common pattern, anti-S-1 stains both the generative cell and the vegetative nuclear envelope. The different staining patterns of the nucleus between anti-S-1 and anti-LMM may be caused by some organization and/or anchorage state of the myosin molecules on the nuclear surface that differs from those on the vesicles and/or organelles.
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PMID:Immunochemical and immunocytochemical identification of a myosin heavy chain polypeptide in Nicotiana pollen tubes. 268 60

We describe the purification of an actin regulatory protein from bovine adrenal medulla. This protein caused a dose-dependent decrease of the specific viscosity of actin solution within 30 s of its addition in a Ca2+-sensitive way. Sedimentation assays and the observation by electron microscopy showed that this effect was ascribable to the fragmentation of actin filaments. This protein apparently promoted nucleation of actin polymerization and increased the critical concentration of actin for polymerization nearly 5-fold, suggesting its binding to the barbed end of actin filaments. The inhibitory effect of this protein on the elongation of actin from the barbed end of the myosin subfragment S1-labeled actin seeds confirmed this suggestion. These properties are similar to those of gelsolin. However, the physicochemical properties of this protein having a single polypeptide chain with a molecular weight of 74,000, a Stokes radius of 3.9 nm, a sedimentation coefficient (s0(20),w) of 4.5 S, and an immunological characterization showed that this protein is different from gelsolin.
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PMID:Purification and characterization of a Ca2+-dependent actin filament severing protein from bovine adrenal medulla. 270 71

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 (L20-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 L20-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 L20-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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PMID:Two isoforms of smooth muscle myosin regulatory light chain in chicken gizzard. 277 58

A calcium- and calmodulin-dependent kinase that represents the majority of the myosin heavy chain kinase activity in chicken intestinal brush borders has been highly purified. The purification steps include gel filtration, high performance chromatography on anion and cation exchangers, and affinity chromatography on calmodulin-Sepharose. The purified kinase consists of a single major, apparently autophosphorylatable polypeptide of 50,000 daltons. The Stokes radius (68 A) and sedimentation coefficient (17.5 S) indicate that it has a molecular weight of approximately 490,000. The kinase catalyzed the incorporation of a maximum of 0.8 mol of phosphate/mol of heavy chain, and essentially no phosphate was incorporated into the light chains. This kinase is distinct from other myosin kinases, but has a number of properties in common with the type II calmodulin-dependent protein kinases.
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PMID:Purification and characterization of a calmodulin-dependent myosin heavy chain kinase from intestinal brush border. 282 19

The unc-22 gene is one of a set of genes identified using classical genetics that affect muscle structure and function in the free-living nematode Caenorhabditis elegans. Since cloning the unc-22 gene by transposon tagging, we have used conventional techniques combined with a set of Tc1 transposon insertion alleles to characterize the gene and its products. The gene extends over more than 20 kb of genomic sequence and produces a transcript of approximately 14 kb. A polyclonal antibody raised against an Escherichia coli beta-galactosidase-unc-22 fusion protein recognizes a polypeptide in nematode extracts that is between 500,000 and 600,000 daltons and labels the muscle A-band in indirect immunofluorescent microscopy. The Tc1-induced alleles have been used at every stage to verify these conclusions. The Tc1 insertions are spread over much of the region that contributes to the mature transcript; in most alleles, Tc1 sequences are incorporated into a composite unc-22-Tc1 transcript. The large protein is either absent or severely reduced in amounts in the mutants. In one case, a truncated polypeptide was also identified. The location of the protein in the A-band, along with earlier genetic data, suggests that the unc-22 product may interact with myosin to regulate its function.
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PMID:Identification and intracellular localization of the unc-22 gene product of Caenorhabditis elegans. 283 27


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