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At least 973 records · Page 54Linked to original sources
PubMed1999

Isolation and characterization of the actin gene from the cellulolytic fungus Humicola grisea and analysis of transcription levels of actin and cellulase genes.

An actin gene was isolated from the cellulolytic fungus Humicola grisea. The gene structure, which has 5 introns in the coding region, is similar to those of the so far cloned fungal actin genes. But there are some differences in intron sizes and codon usage. Transcription levels of actin and cellulase genes were also investigated.

5' Untranslated Regions↗
PubMed1992

Binding of human platelet glycoprotein Ib and actin to fragments of actin-binding protein.

Actin-binding protein (ABP) is degraded into fragments of 190 and 90 kDa by calpain. A monoclonal antibody (MAb TI10) against the 90 kDa fragment of ABP coprecipitated with the glycoprotein Ib (GP Ib) peak observed on crossed immunoelectrophoresis of Triton X-100 extracts of platelets prepared without calpain inhibitors. MAb PM6/317 against the 190 kDa fragment was not coprecipitated with the GP Ib peak under such conditions. The 90 kDa fragment was adsorbed on protein A agarose from extracts that had been preincubated with antibodies to GP Ib. This supports the idea that the GP Ib-ABP interaction resides in the 90 kDa region of ABP. GP Ib was sedimented with the Triton-insoluble actin filaments in trace amounts only, and only after high speed centrifugation (100,000 x g, 3 h). Both the 190 kDa and the 90 kDa fragments of ABP were sedimented with the Triton-insoluble actin filaments.

Actins↗
PubMed1978

Actin from diploid and haploid cells of the myxomycete Physarum flavicomum--comparison with skeletal muscle actin.

Glycerinated diploid microplasmodia of Physarum flavicomum exhibited ATP-dependent contractility typical of actomyosin controlled systems. Actin was isolated from microplasmodia, haploid amoebae-swarm cells, and rabbit skeletal muscle, by classical methods as well as ATP-DEAE cellulose chromatography, and isoelectric focusing. Actins from all three sources had isoelectric points in the pH 6.5-7.0 range, and behaved similarly during the various isolation procedures. SDS-gel electrophoresis revealed that the actin from microplasmodia and muscle had a molecule weight of about 46,000 daltons while the amoebae-swarm cells possessed proteins of molecular weights of about 46,000 and 51,000 daltons.

Actins↗
PubMed1981

[Immunohistochemical localization of actin and myosin in liver, kidney, stomach, heart and skeletal muscle: a reference to a cytoplasmic actin fibrillar network in liver cells (author's transl)].

For immunohistological localizing of actin and myosin in tissue sections, unfixed cryostate sections of rat liver, kidney, stomach, heart, and tongue as well as isolated bovine skeletal myofibrils were incubated with rabbit antibodies against actin respectively myosin from chicken gizzard and detected with anti-rabbit immunoglobulin labeled with fluorescein isothiocyanate. No remarkable differences were found between the 2 antisera. However the results suggested that a fibrillar cytoplasmic net exist especially in hepatocytes and which contains actin and may connect the cell membrane with the endoplasmic reticulum and the nucleus. The net might have static and dynamic functions.

Actins↗
PubMed1990

Fibroblast-mediated contraction in actinically exposed and actinically protected aging skin.

The changes in skin morphology over time are a consequence of both chronologic aging and the accumulation of environmental exposure. Through observation, we know that actinic radiation intensifies the apparent aging of skin. We have investigated the effects of aging and actinic radiation on the ability of fibroblasts to contract collagen-fibroblast lattices. Preauricular and postauricular skin samples were obtained from eight patients aged 49 to 74 undergoing rhytidectomy. The samples were kept separate, and the fibroblasts were grown in culture. Lattices constructed with preauricular fibroblasts consistently contracted more than lattices containing postauricular fibroblasts. The difference in amount of contraction in 7 days between sites was greatest for the younger patients and decreased linearly as donor age increased (r = -0.96). This difference may be due to preauricular fibroblasts losing their ability to contract a lattice as aging skin is exposed to more actinic radiation.

Aged↗
PubMed1988

[The syndrome of chronic actinic dermatitis. Persistent light reaction--actinic reticuloid].

The clinical, histological and photobiological features of persistent light reaction and actinic reticuloid are discussed with reference to the literature. Both conditions are characterized by extreme light sensitivity, have been reported exclusively in elderly men, and are interpreted as a consequence of a photoallergic reaction. In our view, persistent light reaction and actinic reticuloid do not represent separate entities, but rather the two extremes of a single spectrum of disease; in common with other workers, we prefer to call it chronic actinic dermatitis. This opinion is supported by a detailed analysis of three of our patients, who illustrate all variations of this photodermatosis.

Chronic Disease↗
PubMed1992

The structure of the F-actin filament and the actin molecule.

A consensus view on the three-dimensional structure of the F-actin filament and the relative strength of the intersubunit contacts in the filament has been established from an atomic filament model and recent three-dimensional reconstructions from electron micrographs of F-actin filaments. Functional implications of recent structural and biochemical data indicating a rather dynamic filament structure are discussed.

Actin Cytoskeleton↗
PubMed2006

Actin microfilaments regulate vacuolar structures and dynamics: dual observation of actin microfilaments and vacuolar membrane in living tobacco BY-2 Cells.

Actin microfilaments (MFs) participate in many fundamental processes in plant growth and development. Here, we report the co-localization of the actin MF and vacuolar membrane (VM), as visualized by vital VM staining with FM4-64 in living tobacco BY-2 cells stably expressing green fluorescent protein (GFP)-fimbrin (BY-GF11). The MFs were intensively localized on the VM surface and at the periphery of the cytoplasmic strands rather than at their center. The co-localization of MFs and VMs was confirmed by the observation made using transient expression of red fluorescent protein (RFP)-fimbrin in tobacco BY-2 cells stably expressing GFP-AtVam3p (BY-GV7) and BY-2 cells stably expressing gamma-tonoplast intrinsic protein (gamma-TIP)-GFP fusion protein (BY-GG). Time-lapse imaging revealed dynamic movement of MF structures which was parallel to that of cytoplasmic strands. Disruption of MF structures disorganized cytoplasmic strand structures and produced small spherical vacuoles in the VM-accumulating region. Three-dimensional reconstructions of the vacuolar structures revealed a disconnection of these small spherical vacuoles from the large vacuoles. Real-time observations and quantitative image analyses demonstrated rapid movements of MFs and VMs near the cell cortex, which were inhibited by the general myosin ATPase inhibitor, 2,3-butanedion monoxime (BDM). Moreover, both bistheonellide A (BA) and BDM treatment inhibited the reorganization of the cytoplasmic strands and the migration of daughter cell nuclei at early G1 phase, suggesting a requirement for the acto-myosin system for vacuolar morphogenesis during cell cycle progression. These results suggest that MFs support the vacuolar structures and that the acto-myosin system plays an essential role in vacuolar morphogenesis.

Actin Cytoskeleton↗
PubMed2006

Prevalence of actinic keratoses and associated factors in a representative sample of the Italian adult population: Results from the Prevalence of Actinic Keratoses Italian Study, 2003-2004.

OBJECTIVE: The Prevalence of Actinic Keratoses Italian Study (PraKtis) was designed to estimate the point prevalence of actinic keratoses (AKs) and associated factors in a representative sample of the Italian adult population. DESIGN: A representative sample of people 45 years or older was selected from the electoral rolls according to a stratified random sampling design. SETTING: A total of 180 specifically trained interviewers contacted the sampled subjects and conducted face-to-face, computer-assisted interviews and skin assessments. PARTICIPANTS: A total of 12,483 subjects contacted and interviewed from March 1, 2003, through April 30, 2004. MAIN OUTCOME MEASURES: History of AKs and evidence of AKs at the interview. RESULTS: Overall, an estimated 34% of the Italian population reported ever having undergone a dermatological examination. A history of AKs was reported by 0.3% of the total sample. Topical therapy was the most popular treatment according to 39% of subjects, whereas 25% reported that they did not receive therapy. Based on the interviewer's judgment, the point prevalence of AKs was 1.4% (95% confidence interval, 1.2%-1.8%). Forty-two percent of people with AKs were unaware of their condition. The prevalence was higher among men than women and increased steadily with age. The prevalence increased with lighter phenotype and with more severe facial wrinkling. It also increased with the reported number of hours spent in the sun during the week and on holidays. No clear variation was observed according to the reported use of sunscreens. Lesions were usually multiple (median number, 4). There was a strong association between a history of nonmelanoma skin cancers and the presence of AKs (odds ratio, 4.5; 95% confidence interval, 1.8-11.0). CONCLUSIONS: The prevalence of AKs in our study was remarkably lower than expected based on data from the United States and Australia; in Italy, AKs seem to be underdiagnosed and undertreated.

Age Factors↗
PubMed2005

Induction of initial cardiomyocyte alpha-actin--smooth muscle alpha-actin--in cultured avian pregastrula epiblast: a role for nodal and BMP antagonist.

During early cardiogenesis, endoderm-derived bone morphogenetic protein (BMP) induces the expression of both heart-specific transcription factors and sarcomeric proteins. However, BMP antagonists do not inhibit the expression of the "initial heart alpha-actin"--smooth muscle alpha-actin (SMA)--which is first expressed in the anterior lateral mesoderm and then recruited into the initial myofibrils (Nakajima et al. [2002] Dev. Biol. 245:291-303). Therefore, mechanisms that regulate the expression of SMA in the heart-forming mesoderm are not well-understood. Regional explantation experiments using chick blastoderm showed that the posterolateral region of the epiblast differentiated into cardiomyocytes. Posterior epiblast cultured with or without the associated hypoblast showed that interaction between the tissues of these two germ layers at the early pregastrula stage (stages X-XI) was a prerequisite for the expression of SMA. Posterior epiblast that is cultured without hypoblast could also be induced to express SMA if TGF-beta or activin was added to the culture medium. However, neither neutralizing antibodies against TGF-betas nor follistatin perturbed the expression of SMA in cultured blastoderm. Adding BMP to the cultured blastoderm inhibited the expression of SMA, whereas BMP antagonists, such as chordin, were able to induce the expression of SMA in cultured posterior epiblast. Furthermore, adding lefty-1, a nodal antagonist, to the blastoderm inhibited the expression of SMA, and nodal plus BMP antagonist up-regulated the expression of SMA in cultured posterior epiblast. Results indicate that the interaction between the tissues of the posterior epiblast and hypoblast is necessary to initiate the expression of SMA during early cardiogenesis and that nodal and BMP antagonist may play an important role in the regulation of SMA expression.

Actins↗
PubMed1987

On an Mg2+-dependent interaction of actin with glyceraldehyde-phosphate dehydrogenase. The fundamental role of KCl in the organization of F-actin.

In the presence of Mg2+, the formation of actin filaments is hindered by glyceraldehyde-3-phosphate dehydrogenase. This effect, which increases with the square of Mg2+ concentration, is counteracted by 0.15 M KCl. Thus KCl, at concentrations found in the intracellular compartment, appears to be strictly required for the correct formation of actin filaments in all tissues in which the glyceraldehyde-phosphate dehydrogenase concentration is high.

Actins↗
PubMed1984

Towards an alignment of the actin molecule within the actin filament.

Electron micrographs of negatively stained actin filament paracrystals and single-layered filament rafts showing different interfilament spacings have been studied and three-dimensional reconstructions have been computed from them. Lateral ordering of the filaments in rafts was lost when interfilament spacings exceeded 8.5 nm, suggesting this distance as an upper limit for the filament diameter. Further, all reconstructions showed the same structural features at the 3 nm resolution level, except that the filaments from ordered single-layered rafts appeared 10-20% wider than those from multi-layered paracrystals. A comparison between electron microscopical and X-ray filament data, and synthetic filaments generated using different tentative molecular models and/or orientations for actin did not allow a single best model to be selected.

Actins↗
PubMed1985

Selective extraction of Chara actin bundles: identification of actin and two coextracting proteins.

The sub-cortical actin bundles of the alga Chara corallina can be selectively extracted with a low salt solution except when cytochalasin B is present. Proteins with molecular weights of 160000, 43000 and 37000 share this extraction behaviour. While chemical cleavage of the 43000 band indicates that it is actin, the nature of the other proteins is unknown. Although the 37000 protein resembles tropomyosin in molecular weight it lacks tropomyosin's distinctively large change in electrophoretic mobility in the presence of urea.

Actins↗
PubMed2005

Two closely linked variations in actin cytoskeleton pathway in a Chinese pedigree with disseminated superficial actinic porokeratosis.

BACKGROUND: Disseminated superficial actinic porokeratosis (DSAP) is an uncommon autosomal dominant chronic keratinization disorder, characterized by multiple superficial keratotic lesions surrounded by a slightly raised keratotic border. Recently, SSH1 was identified as the DSAP candidate gene. OBJECTIVE: Our purpose was to determine the locus of DSAP and identify the candidate gene(s) of the disease. METHODS: Genome-wide scanning and linkage analysis were performed in a 6-generation Chinese family with DSAP. The coding exons and promoter region of the candidate genes were screened for the nucleotide variations. RESULTS: A missense mutation (p.Ser63Asn) in SSH1 and a variation (dbSNP3759383: G>A) in the promoter region of ARPC3 were closely linked with DSAP in the pedigree. CONCLUSION: Both SSH1 and ARPC3 are involved in the actin cytoskeleton pathway and interacted with adherent junctions in the epidermal cells. We suggested that cytoskeleton disorganization in epidermal cells was likely associated with the pathogenesis of DSAP.

Actins↗
PubMed2003

Structural evidence for the interaction of C-protein (MyBP-C) with actin and sequence identification of a possible actin-binding domain.

C-protein (MyBP-C) is a myosin-binding protein that is usually seen in two sets of seven to nine positions in the C-zones in each half of the vertebrate striated muscle A-band. Skeletal muscle C-protein is a modular structure containing ten sub-domains (C1 to C10) of which seven are immunoglobulin-type domains and three (C6, C7 and C9) are fibronectin-like domains. Cardiac muscle C-protein has an extra N-terminal domain (C0) and also some sequence insertions, one of which provides phosphorylation sites. It is conceivable that C-protein has both a structural and regulatory role within the sarcomere. The precise mode of binding of C-protein to the myosin filament has not been determined. However, detailed ultrastructural studies have suggested that C-protein, which binds to myosin, can give rise to a longer periodicity (about 435A) than the intrinsic myosin filament repeat of 429A. The reason for this has remained a puzzle for over 25 years. Here we show by modelling and computation that the presence of this longer periodicity could be explained if the myosin-binding part of C-protein binds to myosin with the expected 429A repeat, but if there are systematic interactions of the N-terminal end of C-protein with the neighbouring actin filaments in the hexagonal lattice of filaments in the A-band. We also show that if they occur these interactions would probably only arise in defined muscle states. Further analysis of the MyBP-C sequence identifies a possible actin-binding domain in the Pro-Ala-rich sequence found at the N terminus of skeletal MyBP-C and between domains C0 and C1 in the cardiac sequence.

Actins↗
PubMed2000

Actin cytoskeleton: thinking globally, actin' locally.

A class of proteins dubbed pipmodulins bind to and sequester the phospholipid PIP2 in the plasma membrane. Local release of PIP2 controls actin dynamics in specific subcellular regions and plays a critical role in regulating actin-based cell motility and morphogenesis.

Actins↗
PubMedDate not supplied

Actin dynamics: assembly and disassembly of actin networks.

Assembly of branched actin filament networks at the leading edge of migrating cells requires stimulation of the Arp2/3 complex by WASp proteins, in concert with the WASp activators Cdc42, PIP(2) and profilin. Network disassembly and debranching appears to be linked to actin-bound ATP hydrolysis as filaments age.

Actins↗
PubMed2003

The actin-regulating kinase Prk1p negatively regulates Scd5p, a suppressor of clathrin deficiency, in actin organization and endocytosis.

Endocytosis is a dynamic process requiring a network of interacting proteins that assemble and disassemble during cargo capture and vesicle formation. A major mechanism for regulation of this process involves the reversible phosphorylation of endocytic factors. Recently, members of a new kinase family, the Ark/Prk kinases, which include mammalian AAK1 and GAK as well as yeast Prk1p, Ark1p, and Akl1p, were shown to regulate components of the endocytic machinery. These include animal AP-1/AP-2 mu chains and yeast Pan1p (Eps15-like), Sla1p, and epsins, but other potential targets are likely. SCD5, an essential yeast gene, was identified as a suppressor of clathrin deficiency. We also showed that Scd5p is required for normal cortical actin organization and endocytosis, possibly as a targeting subunit for protein phosphatase type 1 (PP1). Scd5p contains a central triple repeat (3R) motif related to a known Prk1p consensus phosphorylation site L/IxxQxTG, except that Q is replaced by T. In this study we demonstrate that the Scd5p 3R sequence is phosphorylated by Prk1p to negatively regulate Scd5p. Furthermore, we show that Prk1p, Ark1p, and Akl1p have different substrate specificities and play distinct roles in actin organization and endocytosis.

Actins↗