In addition to the contractile proteins actin and myosin, filaments of striated muscle contain other that are important for regulating structure interaction two force-generating proteins. thin filaments, troponin tropomyosin form a Ca-sensitive trigger activates normal contraction when intracellular Ca is elevated. thick filament, there several myosin-binding whose functions unclear. Among these protein C (MBP-C). The cardiac isoform contains four phosphorylation sites under control cAMP...

Previous studies established that vaccinia virus could enter cells by fusion with the plasma membrane at neutral pH. However, low pH triggers of virus-infected cells, a hallmark viruses endosomal route. Here, we demonstrate entry mature virions is accelerated brief low-pH treatment and severely reduced inhibitors acidification, providing evidence for predominant low-pH-dependent pathway. Entry cores into cytoplasm, measured expression firefly luciferase, was increased more than 10-fold...

We studied papillary muscle mechanics and energetics, myosin phenotype, ATPase activities in left ventricles from rats bearing a growth hormone (GH)--secreting tumor. 18 wk after tumor induction, animals exhibited dramatic increase body weight (+101% vs. controls) but no change the ventricular weight/body ratio. The maximum isometric force of muscles normalized per cross-sectional area rose markedly (+42%, P less than 0.05 controls), whereas unloaded shortening velocity did not change. This...

The vaccinia virus (VV) A33R gene encodes a highly conserved 23- to 28-kDa glycoprotein that is specifically incorporated into the viral outer envelope. protein expressed early and late after infection, consistent with putative promoter sequences. To determine role of protein, two inducible mutants were constructed, one elements. Decreased expression was associated small plaques formed comets in liquid medium. Using both an antibiotic resistance color marker, deletion mutant, vA33delta,...

Genetic and biochemical studies have provided evidence for an entry/fusion complex (EFC) comprised of at least eight viral proteins (A16, A21, A28, G3, G9, H2, J5, L5) that together with associated protein (F9) participates in entry vaccinia virus (VACV) into cells. The genes encoding these are conserved all poxviruses, expressed late infection, components the mature virion membrane but not required morphogenesis. In addition, one component has intramolecular disulfides formed by poxvirus...

For many viruses, one or two proteins allow cell attachment and entry, which occurs through the plasma membrane following endocytosis at low pH. In contrast, vaccinia virus (VACV) enters cells by both neutral pH routes; four mediate twelve that are associated in a complex conserved all poxviruses dedicated to entry. The aim of present study was determine roles cellular viral initial stages specifically fusion membranes mature virion cell. analysis role components, we used well characterized...

The anterograde pathway, from the endoplasmic reticulum through trans-Golgi network to cell surface, is utilized by trans-membrane and secretory proteins. retrograde which directs traffic in opposite direction, used following endocytosis of exogenous molecules recycling membrane Microbes exploit both routes: viruses typically use pathway for envelope formation prior exiting cell, whereas ricin Shiga-like toxins some nonenveloped entry. Mining a human genome-wide RNA interference (RNAi)...

The mechanisms allowing vaccinia virus to spread from cell are incompletely understood. A34R gene of encodes a glycoprotein that is localized in the outer membranes extracellular virions. small-plaque phenotype an deletion mutant was similar mutants with deletions other envelope genes fail produce Transmission electron microscopy, however, revealed produced numerous particles were labeled antibodies outer-envelope proteins and protein A-colloidal gold. Fluorescence scanning microscopy...

During morphogenesis, poxviruses undergo a remarkable transition from spherical immature forms to brick-shaped infectious particles lacking helical or icosahedral symmetry. In this study, we show that the transitory honeycomb lattice coating lipoprotein membrane of vaccinia virus is formed trimers 62-kD protein encoded by viral D13L gene. Deep-etch electron microscopy demonstrated anti-D13 antibodies bound external coat and fragments were in affinity-purified D13 preparations. Soluble...

Modified vaccinia virus Ankara (MVA) is an approved smallpox vaccine and a promising vector for other pathogens as well cancer therapeutics with more than 200 current or completed clinical trials. MVA was derived by passaging the parental hundreds of times in chick embryo fibroblasts during which it lost ability to replicate human most mammalian cells. Although this replication deficiency important safety feature, genetic basis host restriction not understood. Here, unbiased genome-wide RNAi...

The vaccinia virus A32 open reading frame was predicted to encode a protein with nucleoside triphosphate-binding motif and mass of 34 kDa. To investigate the role this protein, we constructed mutant in which original gene replaced by an inducible copy. recombinant virus, vA32i, has conditional lethal phenotype: infectious formation dependent on isopropyl-beta-D-thiogalactopyranoside (IPTG). Under nonpermissive conditions, synthesized early- late-stage viral proteins, as well DNA that...

Coronary vascular endothelial cells release substances into the coronary circulation that modify contractile system of cardiac myocytes, and myocytes may factors modulate secretion cardioregulatory by cells. This regulatory loop is sensitive to rate flow tissue oxygen tension. In present study, venous effluent from isolated perfused hearts contents have been collected, latter disrupting with perfusion at high pressure. The relative amounts upregulating downregulating in both collections...

ABSTRACT The vaccinia virus H3L open reading frame encodes a 324-amino-acid immunodominant membrane component of particles. Biochemical and microscopic studies demonstrated that the protein was expressed late in infection, accumulated cytoplasmic viral factory regions, associated primarily with amorphous material near immature virions intracellular virion membranes. Localization on surfaces particles anchorage via hydrophobic tail were consistent its extraction by NP-40 absence reducing...

Abstract —Cardiac myofilaments contain proteins that regulate the interaction between actin and myosin. In thick filament, there are several may contribute to regulation of contraction. The myosin binding protein C, or C protein, has 4 sites can be phosphorylated by a Ca 2+ -calmodulin–controlled kinase, kinase A C. Using electron microscopy optical diffraction, we examined structure filaments isolated from rat ventricles with either α β isoform heavy chain (MHC) effect specific...

In hyperpermeable cardiac cells, in which the surface membrane has been made highly permeable to small molecules and ions, resting tension increases when concentration of ATP falls below 200 microM. Peak occurs 10 microM equals 60% maximum Ca-activated force 5 mM ATP. The mitochondria cells can maintain an above if supplied with O2, substrate, ADP, inorganic phosphate (Pi). Removal from bathing solution does not increase as long creatine is present. However Pi cannot lower absence phosphate....

ABSTRACT Crescents consisting of a single lipoprotein membrane with an external protein scaffold comprise the initial structural elements poxvirus morphogenesis. enlarge to form spherical immature virions, which enclose viroplasm proteins destined cores mature virions. Previous studies suggest that L2 participates in recruitment endoplasmic reticulum (ER)-derived membranes virions within assembly sites cytoplasmic factories. Here we show interacts previously uncharacterized 42-amino-acid...

Infectious human papillomavirus 16 (HPV16) L1/L2 pseudovirions were found to remain largely intact during vesicular transport the nucleus. By electron microscopy, capsids with a diameter of 50 nm clearly visible within small vesicles attached mitotic chromosomes and lesser extent interphase nuclei, implying nuclear disassembly. confocal analysis, it was determined that entry assembled L1 is dependent upon presence minor capsid protein, L2, but independent encapsidated DNA. We also...

A membranous fraction that could synthesize viral RNA in vitro the presence of magnesium salt, ribonucleotides, and an ATP-regenerating system was isolated from feline calicivirus (FCV)-infected cells. The enzymatically active component this designated FCV replication complexes (RCs), by analogy to other positive-strand viruses. newly synthesized characterized Northern blot analysis, which demonstrated production both full-length (8.0-kb) subgenomic-length (2.5-kb) molecules similar those...

The vaccinia virus A11R gene has orthologs in all known poxvirus genomes, and the A11 protein been previously reported to interact with putative DNA packaging A32 a yeast two-hybrid screen. Using antisera raised against peptides, we show that was (i) expressed at late times an apparent mass of 40 kDa, (ii) not incorporated into particles, (iii) phosphorylated independently viral F10 kinase, (iv) coimmunoprecipitated A32, (v) localized factory. To determine role test whether it is indeed...

Infectious poxvirus particles are unusual in that they brick shaped and lack symmetry. Nevertheless, an external honeycomb lattice comprised of a capsid-like protein dictates the spherical shape size immature particles. In case vaccinia virus, trimers 63-kDa D13 polypeptides form building blocks lattice. present study, we addressed two questions: how D13, which has no transmembrane domain, associates with virion (IV) membrane to structure this scaffold is removed during subsequent stage...

Morphogenesis of vaccinia virus begins with the appearance crescent-shaped membrane precursors immature virions in cytoplasmic factories. During initial characterization product L2R reading frame, we discovered that it plays an important role crescent formation. The L2 protein was expressed early infection and associated detergent-soluble fraction mature virions, consistent two potential membrane-spanning domains. All chordopoxviruses have homologs, suggesting function. Indeed, were unable...

Significance Poxviruses cause human and epizootic diseases are employed as vaccine vectors. The present investigation provides insights into a key step in poxvirus replication, the assembly of infectious virus particles. Enveloped viruses acquire membranes from cellular organelles; nevertheless, source membrane has been an enigma. Poxvirus occurs cytoplasmic factories, first recognizable structures crescents without discernible connections to membranes. demonstrating was isolation vaccinia...