title: Interaction of smooth muscle calponin and desmin.
abstract: Interaction of smooth-muscle calponin and desmin was analyzed by means of ultracentrifugation, fluorescent spectroscopy and affinity chromatography. At low and intermediate ionic strength (30-50 mM NaCl) calponin is cosedimented with desmin with an apparent dissociation constant 3-15 microM and stoichiometry of 1 calponin/4-6 desmin. Calmodulin decreases the quantity of calponin bound to desmin. Increase of ionic strength up to 150 mM weakens calponin-desmin interaction, but even at this ionic strength part of calponin remains bound to desmin. Calponin increases the rate and extent of fluorescence quenching induced by polymerization of 5-iodoacetamidofluorescein-labeled desmin. Affinity chromatography data indicate that desmin-binding sites are located in the N-terminal 22 kDa fragment of calponin. Since calponin interacts with desmin with an affinity comparable with that of, e.g., tropomyosin and myosin we suppose that calponin-desmin interaction may be important for cytoskeleton organization.
authors.affiliation: Department of Biochemistry, School of Biology, Moscow State University, Russian Federation.
authors.forename: P
authors.initials: P
authors.lastname: Wang
authors.forename: N B
authors.initials: NB
authors.lastname: Gusev
mesh_terms: D000818:Animals; D001665:Binding Sites; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism / Q000494:pharmacology; D002417:Cattle; D002846:Chromatography, Affinity; D003893:Desmin / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D005452:Fluoresceins / Q000737:chemistry; D008840:Microfilament Proteins; D009130:Muscle, Smooth / Q000737:chemistry*; D011108:Polymers; D013050:Spectrometry, Fluorescence; D014461:Ultracentrifugation; D000096985:Calponins
chemical_list: D002135:Calcium-Binding Proteins; D002147:Calmodulin; D003893:Desmin; D005452:Fluoresceins; D008840:Microfilament Proteins; D011108:Polymers; D000096985:Calponins; C015296:5-iodoacetamidofluorescein