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 autoantibodies induced in (C57BL/6 x BALB/c)F1 mice during Trypanosoma cruzi (CL strain) infection were analyzed and compared with natural autoantibodies present in healthy mice. Mice were killed at intervals after infection and their sera were tested by enzyme immunoassay against a panel of self- and non-self-Ag: actin, myoglobin, myosin, tubulin, DNA, and TNP-OVA. The level of IgM and IgG autoantibodies against all Ag started to increase from day 15 until 6 wk after the parasite infection. The high level of all autoantibodies persisted 3 mo postinfection, and 1 yr later, half of the mice still had elevated levels of IgM and IgG autoantibodies, particularly antitubulin IgG antibodies. IgM and IgG were isolated from pools of normal and infected mouse sera and their binding capacity to all Ag was compared. The titers of infected mouse sera were increased and the slopes of both IgM and IgG binding curves of autoantibodies to actin, myosin, and tubulin were greater than those of control mouse sera, indicating higher affinities. The average dissociation constant of the IgG2a autoantibody to mouse tubulin was 5 times lower than that of natural antitubulin IgG2a antibodies. Furthermore, absorption of the IgG from infected mouse sera onto a tubulin immunoadsorbent removed half the reactivity with tubulin and also with myosin, actin and parasite extracts. The eluted antibodies bound the same Ag. When IgG were further analyzed by Western blot on proteolytic fragments of tubulin, we found that antibodies from both groups bound to the same broad spectrum of polypeptide bands. However, additional fragments were recognized by antibodies from infected mice. All these results indicate that the autoantibodies naturally present in mice are significantly affected after infection with T. cruzi, in quantity as well as in specificity and affinity.
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PMID:Comparison between autoantibodies arising during Trypanosoma cruzi infection in mice and natural autoantibodies. 210

Titin is the largest polypeptide yet described (relative molecular mass approximately 3 x 10(6); refs 1, 2) and an abundant protein of striated muscle. Its molecules are string-like and in vivo span from the M to Z-lines. I-band regions of titin are thought to make elastic connections between the thick filament and the Z-line, thereby forming a third type of sarcomere filament. These would centre the A-band in the sarcomere and provide structural continuity in relaxed myofibrils. The A-band region of titin seems to be bound to the thick filament, where it has been proposed to act as a 'molecular ruler' regulating filament length and assembly. Here, we show that partial titin complementary DNAs encode a regular pattern of two types of 100-residue motif, each of which probably folds into a separate domain type. Such motifs are present in several evolutionarily divergent muscle proteins, all of which are likely to interact with myosin. One or both of the domain types is therefore likely to bind to myosin.
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PMID:A regular pattern of two types of 100-residue motif in the sequence of titin. 212 45

Calcium- and calmodulin-regulated ATPase and protein kinase activities are shown to be strongly associated with brain actomyosin. Similar enzymatic activities and an invariable polypeptide profile on sodium dodecyl sulfate-polyacrylamide gel electrophoresis were obtained for brain actomyosin taken through a solubilization-precipitation cycle (1.0-0.1 M KCl), or precipitated from buffers containing 1% Triton X-100 or 10 mM EDTA and 10 mM EGTA. These data suggest a specific complex of brain actomyosin with a protein kinase similar to calmodulin-dependent kinase II, a 190-kDa calmodulin-binding protein (P190), and a calmodulin-like polypeptide. P190 was the major substrate for endogenous calcium-dependent phosphorylation. 125I-Calmodulin overlay technique revealed four major calmodulin-binding polypeptides associated with brain actomyosin: 50- and 60-kDa subunits of the calmodulin-dependent kinase II, P190, and a high molecular weight polypeptide which is probably fodrin. A fraction enriched in P190 had Ca2(+)- and calmodulin-stimulated MgATPase activity, but not myosin-like K-EDTA ATPase activity. The lack of immunological cross-reactivity between brain myosin heavy chain and P190 confirmed that they are distinct molecules.
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PMID:Calmodulin-binding proteins and calcium/calmodulin-regulated enzyme activities associated with brain actomyosin. 213 13

Motile activities such as chemotaxis and phagocytosis, which occur in Dictyostelium cells lacking myosin II, may be dependent upon myosin I. To begin to explore this possibility, we have engineered a disruption of the Dictyostelium myosin I heavy chain (DMIHC) gene described recently (Jung, G., C. L. Saxe III, A. R. Kimmel, and J. A. Hammer III. 1989. Proc. Natl. Acad. Sci. USA. 86:6186-6190). The double-crossover, gene disruption event that occurred resulted in replacement of the middle approximate one-third of the gene with the neomycin resistance marker. The resulting cells are devoid of both the 3.6-kb DMIHC gene transcript and the 124-kD DMIHC polypeptide. DMIHC- cells are capable of chemotactic streaming and aggregation, but these processes are delayed. Furthermore, the rate of phagocytosis by DMIHC- cells is reduced, as assessed by growth rate on lawns of heat-killed bacteria and on the initial rate of uptake of FITC-labeled bacteria. Therefore, this Dictyostelium myosin I isoform appears to play a role in supporting chemotaxis and phagocytosis, but it is clearly not required for these processes to occur. Using a portion of the DMIHC gene as a probe, we have cloned three additional Dictyostelium small myosin heavy chain genes. Comparison of these four genes with three genes described recently by Titus et al. (Titus, M. A., H. M. Warrick, and J. A. Spudich. 1989. Cell Reg. 1:55-63) indicates that there are at least five small myosin heavy chain genes in Dictyostelium. The probability that there is considerable overlap of function between these small myosin isoforms indicates that multiple gene disruptions within a single cell may be necessary to generate a more striking myosin I- phenotype.
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PMID:Generation and characterization of Dictyostelium cells deficient in a myosin I heavy chain isoform. 214 Oct 28

Myocarditis accompanies sublethal mouse cytomegalovirus (MCMV) infection in susceptible BALB/c mice and persists beyond the acute phase of infection, in the absence of demonstrable virus antigen but in the continuing presence of autoantibodies to cardiac muscle. Heart tissue autoantibodies of the IgG class were first detected by ELISA in sera at Days 3-5 post-infection (PI) and persisted to Day 100, in two strains of MCMV-infected mice which are susceptible (BALB/c) and resistant (C57BL/10) to MCMV-induced myocarditis. Analysis by immunoblot showed that autoantibodies in early immune sera (Day 10) from both mouse strains reacted with the contractile proteins troponin, tropomyosin and myosin, as well as with other unidentified polypeptides within normal mouse organ homogenates. However, the dominant reactivity of late immune sera (Day 100) was to a 200,000 molecular weight (MW) polypeptide in muscle homogenates identified as the heavy chain of myosin. Autoantibodies reacting with the cardiac or striated muscle isoforms of myosin were assessed by ELISA in BALB/c and C57BL/10 mice. At Days 28, 56 and 100 PI only the susceptible BALB/c strain had high titres of autoantibodies reacting with the cardiac isoform of myosin. Increasing the virus dose given to C57BL/10 mice resulted in slight increases in titres of anti-myosin antibody; however, the peak antibody titres did not approach those of BALB/c mice and persisting myocarditis did not develop. Absorption experiments showed that cardiac myosin-specific antibodies were present in immune sera from susceptible BALB/c mice at Day 100 but not in resistant C57BL/10 mice by ELISA and immunoblot. These results demonstrate that autoimmunity to myosin is a prominent feature of the humoral autoimmune response following MCMV infection, and that there are differences both in fine isoform specificity and titre of anti-myosin antibodies between strains of mice that develop persisting myocarditis and strains that do not. Cardiac myosin-specific autoantibodies may play an immunopathogenic role in CMV-induced myocarditis.
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PMID:Autoantibodies to cardiac myosin in mouse cytomegalovirus myocarditis. 217 Feb 69

In summary, we have used a multidisciplinary approach to the analysis of actomyosin-based motility during Drosophila embryogenesis. We have documented the movements of early embryogenesis with modern, video methods. We have characterized the cytoplasmic myosin polypeptide, made specific polyclonal antisera to the molecule, studied its distribution during early embryogenesis, cloned and partially characterized the gene that encodes it, and have recently completed the nucleotide sequence of a nearly full length cDNA that encodes the entire protein-coding region. We have initiated studies on myosin function in living embryos both by direct microinjection of antibodies and through classical genetics. To better understand how myosin function is regulated, we have begun analysis of its light chains. Finally, to investigate the molecular mechanism by which its function is integrated into a labile cytoskeleton, whose architecture is constantly changing, we have also investigated Drosophila spectrins. Together, these studies are designed to shed light on the dynamics of biologic form at the cellular level, with current focus on such complex processes as cytokinesis and morphogenesis.
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PMID:Contractile proteins in Drosophila development. 219 98

Charcot-Marie-Tooth disease type 1a (CMT 1a) is an autosomal dominant peripheral neuropathy linked to the DNA markers D17S58 and D17S71, located in the pericentromeric region of the chromosome 17p arm. We analyzed an extended 5-generation Belgian family, multiply affected with CMT 1a, for linkage with eight chromosome 17 markers. The results indicated that the CMT 1a mutation is localized in the chromosomal region 17p11.2-p12 between the marker D17S71 and the gene for myosin heavy polypeptide 2 of adult skeletal muscle.
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PMID:Assignment of the Charcot-Marie-Tooth neuropathy type 1 (CMT 1a) gene to 17p11.2-p12. 222 Aug 8

An Acanthamoeba myosin heavy chain has been identified whose tail domain amino acid sequence distinguishes it from Acanthamoeba myosins IB, IC, and II. The gene for this novel myosin heavy chain spans approximately 6.8 kilobases, is split by 17 introns, and encodes a 177-kDa polypeptide. While the amino-terminal approximately 90 kDa of this polypeptide is highly similar to the globular head sequences of myosins I and II, its approximately 87-kDa tail domain shows essentially no similarity to the tail sequences of either type of myosin. The only exception to this is the carboxyl-terminal approximately 50-amino acid region of the polypeptide, which is homologous to the carboxyl termini of the myosins I. Interestingly, this approximately 50-residue segment has been shown to exist in a diverse family of cytoskeleton-associated proteins that include nonreceptor tyrosine kinases, phospholipase C gamma, and fodrin (Rodaway, A. R. F., Sternberg, M. J. E., and Bentley, D. L. (1989) Nature 342, 624). Sequence analysis indicates that the tail domain of this new myosin is incapable of forming a myosin II-like coiled-coil structure, implying that the protein is single-headed and nonfilamentous. For this reason we have tentatively classified it as a high molecular weight form of myosin I (HMWMI). To determine if HMWMI exists in cells, antiserum was raised against a bacterially expressed fusion peptide made using a cDNA clone encoding most of the unique HMWMI tail domain. This antiserum does not recognize Acanthamoeba myosins IB, IC, or II but does recognize a single polypeptide in whole cell extracts with the mobility predicted for the HMWMI heavy chain. This protein is precipitated from crude extracts using F-actin and released from the pellet by ATP, supporting its classification as a member of the myosin family of proteins.
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PMID:A new Acanthamoeba myosin heavy chain. Cloning of the gene and immunological identification of the polypeptide. 224 10

Since filamentous actin had been shown earlier to exist in lens epithelial and fiber cells, we inquired whether this could represent a contractile system with myosin and other actin-associated proteins. We resolved this question in freshly removed or organ-cultured rabbit and squirrel lens epithelial whole mounts using immunocytochemical techniques and by immunoblots of extracts separated by electrophoresis. In the former, methods were developed using long fixation times and long incubation in primary antibodies and biotinylated second antibodies visualized by streptavidin immunofluorescence and by diaminobenzidine peroxidase. Myosin was found to be localized along the filamentous rays and at central vertices of polygonal arrays situated at the apices of epithelial cells. It was not clear whether myosin and actin occurred together along the same or adjacent filaments in a bundle. Tubulin and vimentin were found deeper in the cells and were not aligned with actin and myosin filaments. Control lens epithelia treated similarly except for deletion of the primary antibodies showed no staining. As positive controls, pieces of glycerinated sartorius muscle exhibited characteristic cross-banded patterns of actin and myosin when incubated with the same reagents used on the lens epithelium. Denatured extracts of rabbit lens epithelium and of cortical fiber cells separated by electrophoresis and transferred to nitrocellulose paper, stained specifically with the same myosin and tubulin antibodies used in the immunocytochemistry experiments. The molecular weight profile of the myosin polypeptide indicated that lens tissue has myosin II. We conclude that a contractile system exists in lens epithelial and cortical fiber cells, although the function is not understood at this time. We conjecture that the system may act to stabilize lens shape by providing contractile tone.
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PMID:Immunocytochemical evidence for an actin-myosin system in lens epithelial cells. 224 32

In intestinal microvilli, the 110K-calmodulin complex is the major component of the cross-bridges which connect the core bundle of actin filaments to the membrane. Our previous work showed that the 110-kDa polypeptide can be divided into three functional domains: a 78-kDa fragment that contains the ATPase activity and the ATP-reversible F-actin-binding site, a 12-kDa fragment required for binding calmodulin molecules, and a terminal 20-kDa domain of unknown function [Coluccio, L. M., & Bretscher, A. (1988) J. Cell Biol. 106, 367-374]. By analysis of limited alpha-chymotryptic cleavage products, we now show that the molecular organization is very similar to that described for the S1 fragment of myosin. The catalytic site was identified by photoaffinity labeling with [5,6-3H]UTP, and fragments binding F-actin were identified by cosedimentation assays. Cleavage of the 78-kDa fragment yielded major fragments of 32 and 45 kDa, followed by cleavage of the 45-kDa fragment to a 40-kDa fragment. Of these, only the 32-kDa fragment was labeled by [5,6-3H]UTP. Physical characterization revealed that the 45- and 32-kDa fragments exist as a complex that can bind F-actin, whereas the 40-kDa/32-kDa complex cannot bind actin. We conclude that the catalytic site is located in the 32-kDa fragment and the F-actin-binding site is present in the 45-kDa fragment; the ability to bind actin is lost upon further cleavage of the 45-kDa fragment to 40 kDa. Peptide sequence analysis revealed that the 45-kDa fragment lies within the molecule and suggests that the 32-kDa fragment is the amino terminus.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mapping of the microvillar 110K-calmodulin complex (brush border myosin I). Identification of fragments containing the catalytic and F-actin-binding sites and demonstration of a calcium ion dependent conformational change. 227 96


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