Molecular properties and functions in vitro of chicken smooth-muscle alpha-actinin in comparison with those of striated-muscle alpha-actinins.
alpha-Actinin purified from chicken gizzard smooth muscle was characterized in comparison with alpha-actinins from chicken striated muscles, or fast-skeletal muscle, slow-skeletal muscle, and cardiac muscle. The gizzard alpha-actinin molecule consisted of two apparently identical subunits with a molecular weight of 100,000 on SDS-polyacrylamide gel electrophoresis, as do striated-muscle alpha-actinins. Its isoelectric points in the presence of urea were similar to the striated-muscle counterparts. Despite these similarities, distinctive amino acid sequences between smooth-muscle alpha-actinin and striated-muscle alpha-actinins were revealed by peptide mapping using limited proteolysis in SDS. Gizzard alpha-actinin was immunologically distinguished from striated-muscle alpha-actinins. Gizzard alpha-actinin formed bundles of gizzard F-actin as well as of skeletal-muscle F-actin, but could not form any cross-bridges between adjacent actin filaments under conditions where skeletal-muscle alpha-actinin could. Temperature-dependent competition between gizzard alpha-actinin and tropomyosin on binding to gizzard thin filaments was demonstrated by electron microscopic observations. Gizzard alpha-actinin promoted Mg2+-ATPase activity of reconstituted skeletal actomyosin, gizzard acto-skeletal myosin, and gizzard actomyosin. This promoting effect was depressed by the addition of gizzard tropomyosin. These findings imply that, despite structural differences between gizzard and striated-muscle alpha-actinin molecules, they function similarly in vitro, and that gizzard alpha-actinin can interact not only with smooth-muscle actin (gamma- and beta-actin) but also with skeletal-muscle actin (alpha-actin).
D000185:Actinin / Q000302:isolation & purification*; D000251:Adenosine Triphosphatases / Q000032:analysis; D000818:Animals; D002645:Chickens; D004120:Dimethyl Suberimidate; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D005895:Gizzard, Avian / Q000032:analysis; D005779:Immunodiffusion; D009124:Muscle Proteins / Q000302:isolation & purification*; D009130:Muscle, Smooth / Q000032:analysis*; D009132:Muscles / Q000032:analysis*; D009206:Myocardium / Q000032:analysis; D009928:Organ Specificity; D010446:Peptide Fragments / Q000032:analysis
D009124:Muscle Proteins; D010446:Peptide Fragments; D000185:Actinin; D004120:Dimethyl Suberimidate; D000251:Adenosine Triphosphatases