title: Use of actin isoform-specific antibodies to probe the domain structure in three smooth muscles.
abstract: We investigated the location of actin isoforms in relation to each other and to filament attachment sites by studying the edge-to-edge distribution of both immunofluorescence and immunogold probes in smooth muscle cells from three sources. Antibodies to alpha- or alpha,gamma-actin labeled uniformly across smooth muscle cells from each source. Antibodies to beta-cytoplasmic actin were concentrated on and near dense bodies, especially in gizzard smooth muscle, but were also located throughout the filament compartment. Double immunofluorescent labeling with antibodies to alpha- or alpha/gamma- and to beta-actin shows overlap of label at dense bodies and attachment plaques. Double immunofluorescent labeling with antibodies to alpha-actinin and to beta-actin identified dense bodies and attachment plaques as sites of colocalization. Immunogold labeling with anti-desmin was most prominent near dense bodies in the gizzard and was widely dispersed in vas deferens and arterial smooth muscle cells. Our results indicate that there is extensive overlap between the locations of contractile and cytoskeletal elements and, thus, do not support the two-domain model of smooth muscle structure. Tissue-specific organizational motif differences were seen when gizzard, vas deferens, and artery were compared and suggest that one model may not apply to these three smooth muscles.
authors.affiliation: Muscle Biology Group, Department of Animal Science, 3116 Molecular Biology Building, Iowa State University, Ames, IA 50011-3260, USA. mstromer@iastate.edu
authors.forename: Marvin H
authors.initials: MH
authors.lastname: Stromer
authors.forename: Mary S
authors.initials: MS
authors.lastname: Mayes
authors.forename: Robert M
authors.initials: RM
authors.lastname: Bellin
mesh_terms: D000199:Actins / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D002645:Chickens; D003893:Desmin / Q000276:immunology / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D005895:Gizzard, Avian / Q000378:metabolism; D007083:Iliac Artery / Q000378:metabolism; D008297:Male; D051379:Mice; D016253:Microscopy, Immunoelectron; D009130:Muscle, Smooth / Q000378:metabolism*; D020033:Protein Isoforms / Q000276:immunology / Q000378:metabolism; D017434:Protein Structure, Tertiary; D013552:Swine; D014649:Vas Deferens / Q000378:metabolism
chemical_list: D000199:Actins; D003893:Desmin; D020033:Protein Isoforms