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Title

The specific NH2-terminal sequence Ac-EEED of alpha-smooth muscle actin plays a role in polymerization in vitro and in vivo

Authors
Goethals, M.
Janmey, P. A.
Gabbiani, F.
Vandekerckhove, J.
Published in The Journal of Cell Biology. 1995, vol. 130, no. 4, p. 887-895
Abstract The blocking effect of the NH2-terminal decapeptide of alpha-smooth muscle (SM) actin AcEEED-STALVC on the binding of the specific monoclonal antibody anti-alpha SM-1 (Skalli, O., P. Ropraz, A. Trzeviak, G. Benzonana, D. Gillessen, and G. Gabbiani. 1986. J. Cell Biol. 103:2787-2796) was compared with that of synthetic peptides modified by changing the acetyl group or by substituting an amino acid in positions 1 to 5. Using immunofluorescence and immunoblotting techniques, anti-alpha SM-1 binding was abolished by the native peptide and by peptides with a substitution in position 5, indicating that AcEEED is the epitope for anti-alpha SM-1. Incubation of anti-alpha SM-1 (or of its Fab fragment) with arterial SM actin increased polymerization in physiological salt conditions; the antibody binding did not hinder the incorporation of the actin antibody complex into the filaments. This action was not exerted on skeletal muscle actin. After microinjection of the alpha-SM actin NH2-terminal decapeptide or of the epitopic peptide into cultured aortic smooth muscle cells, double immunofluorescence for alpha-SM actin and total actin showed a selective disappearance of alpha-SM actin staining, detectable at approximately 30 min. When a control peptide (e.g. alpha-skeletal [SK] actin NH2-terminal peptide) was microinjected, this was not seen. This effect is compatible with the possibility that the epitopic peptide traps a protein involved in alpha-SM actin polymerization during the dynamic filament turnover in stress fibers. Whatever the mechanism, this is the first evidence that the NH2 terminus of an actin isoform plays a role in the regulation of polymerization in vitro and in vivo.
Keywords Actins/immunology/ metabolism/ultrastructureAmino Acid SequenceAnimalsAntibody SpecificityAorta/cytologyBinding, CompetitiveCentrifugationEpitopesImmunoblottingMicroinjectionsMicroscopy, ElectronMicroscopy, FluorescenceMolecular Sequence DataMuscle, Smooth, Vascular/ metabolismOligopeptides/immunology/ metabolismPeptide Fragments/immunologyPolymers/metabolismProtein BindingRatsRats, Wistar
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PMID: 7543902
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Other version: http://jcb.rupress.org/content/130/4/887.full.pdf
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CHAPONNIER, Christine et al. The specific NH2-terminal sequence Ac-EEED of alpha-smooth muscle actin plays a role in polymerization in vitro and in vivo. In: The Journal of Cell Biology, 1995, vol. 130, n° 4, p. 887-895. https://archive-ouverte.unige.ch/unige:11190

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