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. Search for Related Content PubMed PubMed Citation Articles by Blostein, R. Social Bookmarking                      What's this?

Relationships between Erythrocyte Membrane Phosphorylation and Adenosine Triphosphate Hydrolysis

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

Human erythrocyte membranes were incubated with a low concentration of terminally labeled ATP with the aim of detecting a phosphorylated intermediate of adenosine triphosphatase activity. A large portion of material labeled briefly at 37° turned over and had properties consistent with participation in sodium ion-stimulated ATPase activity, including the following: (a) magnesium ions present, addition of sodium ions stimulated an increase in both ³²P bound to trichloracetic acid-precipitated membrane material and the rate of ATP hydrolysis. (b) The Na⁺-activated bound ³²P turned over and correlated quantitatively with the amount of bound ³²P sensitive to hydroxylamine, in agreement with properties of phosphorylated intermediate of ATPase of other preparations. (c) Addition of potassium ions stimulated breakdown of the ³²P bound in the presence of sodium ions.

At 0°, a large portion of material labeled briefly was sensitive to hydroxylamine. Its turnover was apparent upon addition of excess ATP or ADP, but not guanosine triphosphate, deoxyguanosine diphosphate, AMP, or 3-phosphoglycerate. The addition of ethylenediamine tetraacetate allowed dephosphorylation of the bound ³²P to proceed, and it was shown that the approximate rate of turnover was similar to the rate of ATP hydrolysis. Although the addition of sodium ions stimulated an increase in bound ³²P and in ATPase activity at 2 µm ATP concentration, manifestations of altered sensitivity to sodium and potassium ions at 0° have been attributed to temperature-induced changes in conformation of catalytic sites.

The relationship of membrane (¹⁴C)ADP-ATP exchange activity to ATPase activity was investigated. It was found that at least 30% of the exchange activity was associated with material which could be separated from ATP hydrolytic activity and which was not labeled with ³²P after incubation with terminally labeled ATP. This activity did not appear to be related to other membrane activities tested, including nucleoside diphosphokinase, adenylate kinase, and phosphoglycerate kinase.

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

This article has been cited by other articles:

				D. R. Yingst, S.-Y. Yang, and R. Schiebinger Purification of active Na+-K+-ATPase using a new ouabain-affinity column Am J Physiol Cell Physiol, October 1, 1998; 275(4): C1167 - C1177. [Abstract] [Full Text] [PDF]

				A. G. Therien, R. Goldshleger, S. J. D. Karlish, and R. Blostein Tissue-specific Distribution and Modulatory Role of the gamma  Subunit of the Na,K-ATPase J. Biol. Chem., December 19, 1997; 272(51): 32628 - 32634. [Abstract] [Full Text] [PDF]

				G. A. Klassen, R. Blostein, H. D. Brown, S. K. Chattopadhyay, and A. B. Patel Adenosine Triphosphatase and Myopathy Science, January 31, 1969; 163(3866): 492 - 493. [PDF]