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Identification of calmodulin-sensitive Ca(2+)-transporting ATPase in the plasma membrane of bovine corneal epithelial cell.
Reinach, P S; Holmberg, N; Chiesa, R.
Afiliação
  • Reinach PS; Department of Ophthalmology, Washington University School of Medicine, St. Louis, MO.
Biochim Biophys Acta ; 1068(1): 1-8, 1991 Sep 10.
Article em En | MEDLINE | ID: mdl-1832560
ATP-dependent Ca2+ uptake was characterized in a plasma membrane enriched fraction obtained from the bovine corneal epithelium. This uptake essentially represented intravesicular accumulation because 72% of the Ca2+ content was releasable following exposure to 10(-6) M A23187. The substrate and Ca2+ requirements for maximal transport activity were similar to those described in the red blood cell because: (1) exogenous calmodulin (3 microM) significantly decreased the apparent Km for Ca2+ to 0.31 microM and increased the rate of Ca2+ uptake; (2) a hydroxylamine labile Ca(2+)-dependent phosphoenzyme intermediate was identified with an apparent molecular size of 140 kDa; (3) Ca(2+)-dependent binding of 125I-labelled calmodulin to this protein was demonstrated which could be antagonized with a calmodulin antagonist, trifluoperazine. These results show that the plasma membrane contains an ATP-dependent Ca2+ transporter. However, its relationship to a previously described high affinity form of Ca(2+)-stimulated Mg(2+)-dependent ATPase is not apparent because their [Mg2+] requirements to elicit maximal activity differed by two orders of magnitude.
Assuntos
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Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Calmodulina / Proteínas de Transporte / Membrana Celular / ATPases Transportadoras de Cálcio / Córnea Tipo de estudo: Diagnostic_studies / Prognostic_studies Limite: Animals Idioma: En Ano de publicação: 1991 Tipo de documento: Article
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Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Calmodulina / Proteínas de Transporte / Membrana Celular / ATPases Transportadoras de Cálcio / Córnea Tipo de estudo: Diagnostic_studies / Prognostic_studies Limite: Animals Idioma: En Ano de publicação: 1991 Tipo de documento: Article