HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Blostein, R. Articles by Whittington, E. S. Search for Related Content PubMed PubMed Citation Articles by Blostein, R. Articles by Whittington, E. S. Social Bookmarking                      What's this?

Studies of High Potassium and Low Potassium Sheep Erythrocyte Membrane Sodium-Adenosine Triphosphatase

INTERACTIONS WITH OLIGOMYCIN, ADENOSINE TRIPHOSPHATE, SODIUM, AND POTASSIUM

From the ¹ From The Division of Hematology, McGill University Clinic, Royal Victoria Hospital, and the Department of Experimental Medicine, McGill University, Montreal, Quebec, Canada

The effects of oligomycin on Na⁺-ATPase of high K (HK) and low K (LK) sheep erythrocyte membranes have been investigated. Activation of LK Na⁺-ATPase is observed with ATP 0.2 µm; activation of HK is observed with ATP 0.02 µm. Inhibition occurs with higher ATP. At 0.2 µm ATP, oligomycin stimulation of LK Na⁺-ATPase is associated with a 3- to 4-fold increase in the ³²P-"intermediate;" inhibition of HK is associated with only a slight increase (1.3-fold) in ³²P-"intermediate." The effects of oligomycin are similar for HK and LK in that activation occurs at low catalytic rates ( 20 pmoles mg^-1 min^-1); inhibition occurs at higher rates, irrespective of the means of altering the rate (varying ATP or Na⁺ concentration, or both; stimulation of LK with specific isoimmune antiserum). Oligomycin counteracts K⁺-inhibition (LK) and K⁺ counteracts oligomycin inhibition (HK). The results are consistent with a reaction sequence involving oligomycin-sensitive conformational changes of phosphorylated and probably unphosphorylated intermediate, i.e. [see PDF for equation] and [see PDF for equation] the resulting shift in equilibrium can, at low catalytic rates, be evidenced in stimulation of Na⁺-ATPase.

Interaction of HK and LK Na⁺-ATPase with Na⁺, K⁺, and ATP are interdependent and markedly different for the two; at constant ATP (0.2 µm), HK is more sensitive to activation by Na⁺ and less sensitive to inhibition by K⁺ than LK ATPase. Although effects of both K⁺ and oligomycin are dependent on ATP concentration, a difference in affinity for ATP in addition to, or as a result of, a different relative affinity for Na⁺ and K⁺ may be the basis for the distinctions between HK and LK membranes.

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

This article has been cited by other articles:

				S. B. Kaufman, R. M. Gonzalez-Lebrero, R. C. Rossi, and P. J. Garrahan Binding of a Single Rb+ Increases Na+/K+-ATPase, Activating Dephosphorylation without Stoichiometric Occlusion J. Biol. Chem., June 9, 2006; 281(23): 15721 - 15726. [Abstract] [Full Text] [PDF]