Journal of Histochemistry and Cytochemistry Priciples for Free Access to Science
  Search:   
    >> Advanced Search

Guidelines | Subscriptions | About | exPRESS - Current - Archive | Business Information | Contact
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Taffarel, M.
Right arrow Articles by Vieyra, A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Taffarel, M.
Right arrow Articles by Vieyra, A.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati  
What's this?

Localization and cation dependence of a Ca2+- or Mg2+-ATPase from electrocytes of Electrophorus electricus, L

M Taffarel, T Coelho-Sampaio, A Teixeira-Ferreira, C Somlo, W De Souza, RD Machado and A Vieyra

Departamento de Histologia e Embriologia, Universidade Federal do Rio de Janeiro, Brasil.

Electrocyte membranes of Electrophorus electricus exhibit high ATPase activity, as demonstrated by cytochemical and biochemical techniques. This activity is visualized as electron-dense deposits in electron micrographs, and appears to be localized only at the innervated face of the electrocyte. ATP hydrolysis can be detected cytochemically or biochemically only in the presence of calcium or magnesium. The effects of Ca or Mg on ATPase activity can be described by Michaelis-like functions with similar apparent Km values for Ca and Mg (0.41 mM and 0.23 mM, respectively). Vmax, however, is fivefold higher in the presence of Mg. The effects of the two cations are not additive, and pH dependence of ATP hydrolysis is identical in the presence of Ca or Mg (maximal at pH 8-9). Therefore, it can be concluded that Ca and Mg activate the same enzyme, the differences in Vmax being attributable to influences in kcat.

Volume 37, Issue 7, pp. 953-959, 07/01/1989
Copyright © 1989 by The Histochemical Society


Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati    What's this?


This article has been cited by other articles:


Home page
 J. Biol. Chem.Home page
R. H. F. Valverde, G. G. Tortelote, T. Lemos, E. Mintz, and A. Vieyra
Ca2+/Calmodulin-dependent Protein Kinase II Is an Essential Mediator in the Coordinated Regulation of Electrocyte Ca2+-ATPase by Calmodulin and Protein Kinase A
J. Biol. Chem., August 26, 2005; 280(34): 30611 - 30618.
[Abstract] [Full Text] [PDF]



Guidelines | Subscriptions | About | exPRESS - Current - Archive | Business Information | Contact
The Journal of Histochemistry & Cytochemistry is owned, published, and licensed by The Histochemical Society © 1989