title: Isolation and characterization of 190K protein from aorta smooth muscle.
abstract: Molecular assemblies of actin and myosin for the contractility of smooth muscle are quite different from those of striated muscle. Another striking difference is that vascular smooth muscle has a potential to transform to migratory synthetic cell type. At this point of view, smooth muscle cell has properties similar to those of non-muscle. In fact, myosin Ic, a single headed unconventional myosin, was identified in aorta smooth muscle. During the studies on myosin Ic, we have found another calmodulin related 190kDa protein. This protein binds to calmodulin irrespective on calcium ion and to F-actin in an ATP independent manner. Furthermore, the F-actin binding stoichiometry diminished to half upon the addition of exogenous calmodulin. Partial amino acid sequence indicated a high homology to those of GRD (GTPase Related Domain) of human brain IQGAP1. Western blot analysis using anti-human IQGAP1 antibody also indicated a strong cross-reactivity with the protein. We have tested the protein with respect to the characteristic F-actin gelation by IQGAP1. In the presence of cdc42 and GTPgammaS, 190kDa protein could cause a high viscosity of F-actin. These data indicate a close similarity to human brain IQGAP1. The presence of IQGAP1 in aorta smooth muscle suggests contributions for cellular processes such as actin reorganization during contraction-relaxation cycle, association of cytoskeletal structure to cell membrane, organelle movement.
authors.affiliation: Muroran Institute of Technology, Department of Applied Chemistry, Muroran, Hokkaido 050-8585, Japan.
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Yan
authors.forename: Naoki
authors.initials: N
authors.lastname: Yoshinaga
authors.forename: Naoki
authors.initials: N
authors.lastname: Niida
authors.forename: Yoh
authors.initials: Y
authors.lastname: Okamoto
mesh_terms: D000199:Actins / Q000737:chemistry / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D001011:Aorta / Q000378:metabolism*; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000737:chemistry; D002352:Carrier Proteins / Q000737:chemistry; D002852:Chromatography, Ion Exchange; D064211:Connectin; D003599:Cytoskeleton / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007477:Ions; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000737:chemistry* / Q000502:physiology; D009130:Muscle, Smooth / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism; D024461:Myosin Type I; D009218:Myosins / Q000737:chemistry; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012685:Sepharose / Q000494:pharmacology; D013552:Swine; D013997:Time Factors; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020703:ras GTPase-Activating Proteins
chemical_list: D000199:Actins; D002147:Calmodulin; D002352:Carrier Proteins; D064211:Connectin; C101203:IQ motif containing GTPase activating protein 1; D007477:Ions; C577299:MYOM1 protein, human; D009124:Muscle Proteins; D020703:ras GTPase-Activating Proteins; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D000255:Adenosine Triphosphate; D012685:Sepharose; D024461:Myosin Type I; C460367:MYO1C protein, human; D009218:Myosins; D020764:cdc42 GTP-Binding Protein; D002118:Calcium