Intracellular localization of the 55-kD actin-bundling protein in cultured cells: spatial relationships with actin, alpha-actinin, tropomyosin, and fimbrin.
The 55-kD protein is a new actin-bundling protein purified from HeLa cells (Yamashiro-Matsumura, S., and F. Matsumura, 1985, J. Biol. Chem., 260:5087-5097). We have prepared monoclonal antibodies against the 55-kD protein and examined its intracellular localization, as well as its spatial relationships with other components of microfilaments in cultured cells by double-label immunofluorescence. The localization of the 55-kD protein is similar to that of actin. The antibody to the 55-kD protein stained strongly both microspikes and stress fibers. The 55-kD protein was found from the basal portions to the extremities of microspikes while alpha-actinin was localized only in the basal portions. In stress fibers, the 55-kD protein was found rather continuously in comparison to the periodic localizations of alpha-actinin and tropomyosin. Although fimbrin is located in microspikes and ruffling membranes, fimbrin is hardly found in stress fibers unlike the 55-kD protein. These observations coupled with the actin-bundling activity of the 55-kD protein imply that the 55-kD protein is involved in the formation of microfilament bundles in both microspikes and stress fibers.
D008841:Actin Cytoskeleton / Q000648:ultrastructure; D000185:Actinin / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D000818:Animals; D000911:Antibodies, Monoclonal; D002352:Carrier Proteins / Q000378:metabolism*; D002451:Cell Compartmentation; D002478:Cells, Cultured; D005455:Fluorescent Antibody Technique; D018260:Gelsolin; D005849:Gerbillinae; D006801:Humans; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008840:Microfilament Proteins; D008970:Molecular Weight; D051381:Rats; D014335:Tropomyosin / Q000378:metabolism*
D000199:Actins; D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D018260:Gelsolin; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D008840:Microfilament Proteins; D014335:Tropomyosin; C016953:brevin; C026742:plastin; D000185:Actinin