title: Alpha1-syntrophin has distinct binding sites for actin and calmodulin.
abstract: Overlay and co-sedimentation assays using recombinant alpha1-syntrophin proteins revealed that two regions of alpha1-syntrophin, i.e. aa 274-315 and 449-505, contain high-affinity binding sites for F-actin (Kd 0.16-0.45 microM), although only a single high-affinity site (Kd 0.35 microM) was detected in the recombinant full-length syntrophin. We also found that actomyosin fractions prepared from both cardiac and skeletal muscle contain proteins recognized by anti-syntrophin antibody. These data suggest a novel role for syntrophin as an actin binding protein, which may be important for the function of the dystrophin-glycoprotein complex or for other cell functions. We also found that alpha1-syntrophin binds calmodulin at two distinct sites with high (Kd 15 nM) and low (Kd 0.3 microM) affinity.
authors.affiliation: Department of Molecular Physiology, National Cardiovascular Center Research Institute, Suita, Osaka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Iwata
authors.forename: Y
authors.initials: Y
authors.lastname: Pan
authors.forename: T
authors.initials: T
authors.lastname: Yoshida
authors.forename: H
authors.initials: H
authors.lastname: Hanada
authors.forename: M
authors.initials: M
authors.lastname: Shigekawa
mesh_terms: D000199:Actins / Q000378:metabolism*; D000205:Actomyosin / Q000302:isolation & purification; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D002135:Calcium-Binding Proteins; D002147:Calmodulin / Q000378:metabolism*; D006224:Cricetinae; D016189:Dystrophin / Q000502:physiology; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D009124:Muscle Proteins / Q000737:chemistry / Q000378:metabolism*; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000378:metabolism*
chemical_list: D000199:Actins; D002135:Calcium-Binding Proteins; D002147:Calmodulin; D016189:Dystrophin; D008565:Membrane Proteins; D009124:Muscle Proteins; D011993:Recombinant Fusion Proteins; C091825:syntrophin alpha1; D000205:Actomyosin