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Localization of the calcium-sensitive actin monomer binding site in gelsolin to segment 4 and identification of calcium binding sites.
Pope, B; Maciver, S; Weeds, A.
Afiliación
  • Pope B; MRC Laboratory of Molecular Biology, Cambridge, U.K.
Biochemistry ; 34(5): 1583-8, 1995 Feb 07.
Article en En | MEDLINE | ID: mdl-7849017
ABSTRACT
Gelsolin is composed of six repeating segments of sequence (G1-6) and contains three distinct actin binding sites, two that bind to G-actin and one that binds to filaments. The calcium-dependent actin monomer binding site present in the carboxyl-terminal half of the protein (G4-6) plays a critical role both in the cooperative binding of actin by gelsolin and in its nucleating activity. Here we have localized this actin binding site to segment 4 (G4) by expressing the segments G4, G4-5, G5, and G5-6 in Escherichia coli and analyzing their actin binding properties. In addition we have measured their calcium binding. G4-5 and G5-6 each bind a single calcium ion, but there is no binding by G4 or G5. The affinity of binding by G5-6 is 10 times higher than that of G4-5, and calcium binding by G4-6 shows two sites of different affinity. Thus each actin binding site of gelsolin is restricted to a single segment (G1, G2, and G4), but the nonbinding segments G5 and G6 play an important role in the calcium regulation of actin binding and other activities of gelsolin.
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Bases de datos: MEDLINE Asunto principal: Calcio / Actinas / Gelsolina Tipo de estudio: Diagnostic_studies / Prognostic_studies Idioma: En Revista: Biochemistry Año: 1995 Tipo del documento: Article País de afiliación: Reino Unido
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Bases de datos: MEDLINE Asunto principal: Calcio / Actinas / Gelsolina Tipo de estudio: Diagnostic_studies / Prognostic_studies Idioma: En Revista: Biochemistry Año: 1995 Tipo del documento: Article País de afiliación: Reino Unido