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At least 613 records · Page 34Linked to original sources
PubMed1994

Multiple isoelectric variants of flightin in Drosophila stretch-activated muscles are generated by temporally regulated phosphorylations.

Drosophila stretch-activated flight muscles contain flightin, a novel myofibrillar protein that interacts with myosin filaments. We have identified eleven flightin isoelectric variants that can be subdivided into phosphorylated and non-phosphorylated subclasses. Flight muscles of late pupal stage P15, at which time myofibrillogenesis has been completed but the muscle has yet to be used, contain primarily non-phosphorylated variants. A dramatic increase in flightin phosphorylation occurs subsequent to eclosion. As the young adult matures, increasingly phosphorylated variants are generated following a precise ontogenetic progression. Adults 5-6 h old and older contain the entire set of flightin isoelectric variants. All nine phosphovariants remain metabolically active throughout adult life as evidenced by their ability to incorporate radioactive phosphate in older adults. Our results suggest the possibility that all nine phosphorylated variants originate from a single precursor by sequential phosphorylation. Phosphorylation of flightin may thus serve both structural and regulatory functional roles.

Animals↗
PubMed1994

Alterations in flightin phosphorylation in Drosophila flight muscles are associated with myofibrillar defects engendered by actin and myosin heavy-chain mutant alleles.

Flightin is a 20-kD myofibrillar protein found in the stretch-activated flight muscles of Drosophila melanogaster. Nine of the eleven isoelectric variants of flightin are generated in vivo by multiple phosphorylations. The accumulation of these isoelectric variants is affected differently by mutations that eliminate thick filaments or thin filaments. Mutations in the myosin heavy-chain gene that prevent thick filament assembly block accumulation of all flightin variants except N1, the unphosphorylated precursor, which is present at much reduced levels. Mutations in the flight muscle-specific actin gene that block actin synthesis and prevent thin filament assembly disrupt the temporal regulation of flightin phosphorylation, resulting in premature phosphorylation and premature accumulation of flightin phosphovariants. Cellular fractionation of fibers that are devoid of thin filaments show that flightin remains associated with the thick filament-rich cytomatrix. These results suggest that flightin is a structural component of the thick filaments whose regulated phosphorylation is dependent upon the presence of thin filaments.

Actin Cytoskeleton↗
PubMedDate not supplied

Hepatitis B virus core protein interacts with the C-terminal region of actin-binding protein.

Hepatitis B viral core protein is present in the nucleus and cytoplasm of infected hepatocytes. There is a strong correlation between the intrahepatic distribution of core protein and the viral replication state and disease activity in patients with chronic hepatitis. To understand the role of core protein in the pathogenesis of HBV, we used a yeast two-hybrid system to search for cellular proteins interacting with the carboxyl terminus of core protein, as this region is involved in a number of important functions in the viral replication cycle including RNA packaging and DNA synthesis. A cDNA encoding the extreme C-terminal region of human actin-binding protein, ABP-276/278, was identified. This interaction was further confirmed both in vitro and in vivo. In addition, the extreme C-terminal region of ABP-276/278 interacted with the nearly full-length HBV core protein. Since this region is present in both the core and the precore proteins, it is likely that both core and precore proteins of HBV can interact with the C-terminal region of ABP-276/278. The minimal region of ABP-276/278 which interacted with the HBV core protein was the C-terminal 199 amino acid residues which correspond to part of the 23rd repeat, the entire 24th repeat and the intervening hinge II region in ABPs. The potential functional outcome of ABP interaction in HBV replication and its contribution to the pathological changes seen in patients with chronic HBV infection are discussed.

Amino Acid Sequence↗
PubMed2004

Mosaic mutations of the FLN1 gene cause a mild phenotype in patients with periventricular heterotopia.

X-linked periventricular nodular heterotopia (PNH) (OMIM 300049) is a neuronal migration disorder, associated with mutations of the FLN1 gene (Xq28), accompanied by severe epilepsy and normal to mildly impaired cognitive function in affected women. The recurrence risk has been estimated to be 50% in daughters of affected women, with early post-natal lethality in boys. Mutation analysis [denaturing high-performance liquid chromatography (DHPLC) and sequencing], performed in a woman and a man with PNH, was suggestive of somatic mosaicism. Both patients were investigated using single nucleotide primer extension (SNuPE) and DHPLC. To better characterize mosaicism in the affected man, SNuPE-DHPLC analysis was also performed on a pool of hair roots and single hair roots. The affected woman had features of PNH on magnetic resonance imaging. She had well-controlled epilepsy and normal cognitive function. She was mosaic for a nucleotide insertion (c.568_569ingG). SNuPE-DHPLC findings showed 17% of mutant allele. The affected man had classical PNH and was mosaic for an A>G substitution (intron 11 acceptor splice site). SNuPE-DHPLC on both leukocyte and hair root DNA revealed 42% and 69% of mutant allele. Single hair root analysis confirmed that this patient did not harbor the mutation in all ectodermal derivative cells. His daughter had not inherited the mutation. Phenotypic heterogeneity associated with X-linked PNH may depend on the type of mutation, its location on the protein, as well as on somatic mosaicism. Mosaicism can influence the recurrence risk rates in affected women. Mosaic mutations in men may not be transmitted to their daughters, masking the X-linked nature of the disorder.

Adult↗
PubMed1987

Immunoreactive forms of caldesmon in cultivated human vascular smooth muscle cells.

150 kDa caldesmon was shown to be characteristic of vascular smooth muscle cells in normal tissue rather than in subculture. Subcultured smooth muscle cells from human aorta contained only the 70 kDa immunoreactive form of caldesmon. During the course of primary culture the amount of 150 kDa caldesmon as well as metavinculin decreased significantly whilst 70 kDa caldesmon became the predominant form, and by the onset of cell division the 150 kDa form was practically substituted by 70 kDa caldesmon. The data show that the predominance of 150 kDa caldesmon is characteristic of contractile smooth muscle cells, while in proliferating cells 70 kDa caldesmon is expressed.

Aorta↗
PubMed1984

Sensitive visualization of antigen-antibody reactions in dot and blot immune overlay assays with immunogold and immunogold/silver staining.

The use of colloidal gold and colloidal gold followed by silver enhancement as marker for dot or blot immune overlays is described. Colloidal gold probes concentrating at the sites of immune reaction gradually develop a pinkish colour during incubation that can be seen with the naked eye. With a physical developer, very high sensitivity and contrast is obtained by silver precipitation on the gold marker. Comparison of the immunogold and immunogold/silver staining methods with the indirect, PAP and ABC immunoperoxidase methods demonstrates that colloidal gold probes are excellent markers for immune overlay assays.

Animals↗
PubMed2004

Calcium receptor-mediated intracellular signalling.

As a G protein-coupled receptor (GPCR), the extracellular calcium-sensing receptor (CaR) responds to changes in extracellular free calcium concentration by inducing intracellular signalling. These CaR-induced signals then specifically modulate cellular functions such as parathyroid hormone secretion from the parathyroid glands and calcium reabsorption in the kidney and thus to understand how the CaR functions one must understand how it signals. CaR-induced signalling involves intracellular Ca2+ mobilisation/oscillations as well as the activation of various phospholipases and protein kinases and the suppression of cAMP formation. This review will detail the intracellular pathways by which the CaR is believed to elicit its physiological functions and summarises the evidence for cell- and agonist-specific differential signalling.

Animals↗
PubMed2006

Cell mechanics: filaminA leads the way.

Actin filaments are thought to be the major structural components of most eukaryotic cells, but reconstituted actin networks have yet to account for the remarkable strength exhibited by cellular networks. A new study has found that reconstituted networks that include the cross-linker filaminA can replicate many of the mechanical properties of cells if they are stressed prior to mechanical measurement.

Actin Cytoskeleton↗
PubMed2002

Association of dopamine D(3) receptors with actin-binding protein 280 (ABP-280).

Proteins that bind to G protein-coupled receptors have been identified as regulators of receptor localization and signaling. In our previous studies, a cytoskeletal protein, actin-binding protein 280 (ABP-280), was found to associate with the third cytoplasmic loop of dopamine D(2) receptors. In this study, we demonstrate that ABP-280 also interacts with dopamine D(3) receptors, but not with D(4) receptors. Similar to the dopamine D(2) receptor, the D(3)/ABP-280 association is of signaling importance. In human melanoma M2 cells lacking ABP-280, D(3) receptors were unable to inhibit forskolin-stimulated cyclic AMP (cAMP) production significantly. D(4) receptors, however, exhibited a similar degree of inhibition of forskolin-stimulated cAMP production in ABP-280-deficient M2 cells and ABP-280-replent M2 subclones (A7 cells). Further experiments revealed that the D(3)/ABP-280 interaction was critically dependent upon a 36 amino acid carboxyl domain of the D(3) receptor third loop, which is conserved in the D(2) receptor but not in the D(4) receptor. Our results demonstrate a subtype-specific regulation of dopamine D(2)-family receptor signaling by the cytoskeletal protein ABP-280.

Adenylyl Cyclase Inhibitors↗
PubMed2000

Identification of actin binding protein, ABP-280, as a binding partner of human Lnk adaptor protein.

Human Lnk (hLnk) is an adaptor protein with multiple functional domains that regulates T cell activation signaling. In order to identify cellular Lnk binding partners, a yeast two-hybrid screening of human spleen cDNA library was carried out using human hLnk as bait. A polypeptide sequence identical to the C-terminal segment of the actin binding protein (ABP-280) was identified as a hLnk binding protein. The expressed hLnk and the FLAG tagged C-terminal 673 amino acid residues of ABP-280 or the endogenous ABP-280 in COS-7 cells could be co-immunoprecipitated using antibodies either to hLnk, FLAG or ABP-280, respectively. Furthermore, immunofluorescence confocal microscope showed that hLnk and ABP-280 co-localized at the plasma membrane and at juxtanuclear region of COS-7 cells. In Jurkat cells, the endogenous hLnk also associates with the endogenous ABP-280 indicating that the association of these two proteins is physiological. The interacting domains of both proteins were mapped using yeast two-hybrid assays. Our results indicate that hLnk binds to the residues 2006-2454 (repeats 19-23C) of ABP-280. The domain in hLnk that associates with ABP-280 was mapped to an interdomain region of 56 amino acids between pleckstrin homology and Src homology 2 domains. These results suggest that hLnk may exert its regulatory role through its association with ABP-280.

Actins↗
PubMed1981

The association of rhodamine - labelled alpha-actinin with actin bundles in demembranated cells.

Rhodamine-labelled alpha-actinin was specifically bound to actin containing filament bundles of demembranated fibroblasts, and was particularly associated with their termini. Optimal binding of rhodamine-alpha-actinin occurred at pH 6.0 - 6.2 and could be abolished by the addition of unlabeled alpha-actinin or myosin subfragment 1. The spatial relationships between the decorating alpha-actinin and several actin associated proteins was determined by double fluorescence microscopy.

Actinin↗
PubMed2002

Brain development and the genetics of brain development.

The progress made in the understanding of the genetics of human brain malformations has lead to insight into the formation of brain and into mechanisms of disease affecting brain. It bears upon neurologists and geneticists to recognize the patterns of diseases of brain formation, to properly diagnose such disorders, to assess the recurrence risk of these malformations, and to guide families with appropriate expectations for outcomes. This article may serve as a guide to neurologists in their approach to these disorders. Because this area is one of rapid progress, the clinician is advised to seek more current information that may be available through on-line databases and other sources.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed2000

Focal adhesions - the cytoskeletal connection.

Cellular contacts with the extracellular matrix are regulated by the Rho family of GTPases through their effects on both the actin and the microtubule cytoarchitecture. Recent genetic, biochemical and structural data have highlighted the role played by a subset of actin-binding proteins in coupling integrins to cytoskeletal actin and in assembling signalling complexes that are important for cell motility and cell proliferation.

Actins↗
PubMedDate not supplied

Dietary effects of copper and iron deficiency on rat intestine: a differential display proteome analysis.

Copper and iron are cofactors of many metallo-proteins that accomplish vital functions, such as oxygen and electron transport. Specific metabolic pathways have been selected through evolution, although still not fully elucidated, to confine the dangerous reactivity of their free ionic forms. Inadequate supply of both metals can severely affect basic physiological functions. A differential analysis of the rat intestinal proteome evidenced the following dietary copper- and iron-deficiencies, i.e., significant changes in the levels of proteins belonging to different functional classes (glucose and fatty acid metabolism, molecular chaperones, cytoskeleton plasticity, vitamin transporters). The presented results bring new perspectives to understand the role of copper and iron in the metabolic pathways and provide novel diagnostic tools to characterize the effects of subclinical deficiencies of both metals in unbalanced nutritional disorders.

Animals↗
PubMed2004

Phenotype matters.

Explore the source record for details and available documents.

Bone Development↗
PubMed2006

Postzygotic mutation and germline mosaicism in the otopalatodigital syndrome spectrum disorders.

The otopalatodigital syndrome (OPD) spectrum disorders are a heterogeneous group of skeletal dysplasias caused by mutations in the X-linked gene, FLNA. All OPD spectrum disorders (otopalatodigital syndromes types 1 and 2, frontometaphyseal dysplasia and Melnick-Needles syndrome) exhibit significant interfamilial variability in their expressivity, especially in female subjects. Factors contributing to this may include allelic heterogeneity, variation in the degree of skewing of X inactivation or, conceivably, mosaicism for the underlying causative mutation. We report here monozygotic twin sisters who are discordant for the severe phenotype, Melnick-Needles syndrome, associated with the heterozygous mutation, 3596C>T. We also describe two brothers with otopalatodigital syndrome type 1 due to the FLNA mutation 620G>A. The mutation is not detectable in the blood leucocytes of their clinically unaffected mother, indicating that she is a germline mosaic for the condition. The description of somatic mutations and germline mosaicism in FLNA has implications for clinical and molecular diagnosis, phenotypic expression and genetic counseling of families with these disorders.

Adolescent↗