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On the mechanism of stimulation of the Na/K pump of LK sheep erythrocytes by anti-L antibody.
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MedLine Citation:
PMID:  2442296     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Studies were undertaken to explore the mechanism of stimulation of the Na/K pump in LK sheep erythrocytes by anti-L antibody. First, the numbers of functioning pump sites were determined by correlating [3H]ouabain binding with levels of inhibition of the pump. Untreated (control) cells had approximately 41 pumps per cell, and anti-L treatment caused an increase in the number of functioning pumps to approximately 85 per cell. Reducing the intracellular K concentration, [K]c, to near zero caused an increase in the number of pumps in control cells, but not in anti-L cells, such that the numbers of pumps per cell were about the same in the two cell types. These results led to the prediction that Kc is a noncompetitive inhibitor of the pump in control cells, and that anti-L stimulates the pump and increases number of functioning pumps by reducing noncompetitive inhibition by Kc. Kinetic studies were undertaken to test this prediction: activation of the pump by increasing [Na]c was measured at three fixed levels of [K]c. In control cells, the apparent maximum velocity of the pump (J'max) was reduced approximately threefold by raising [K]c from 0.2 to 9 mmol/liter cells, demonstrating noncompetitive inhibition by Kc. In anti-L cells, J'max did not vary with [K]c, which shows that, as predicted, anti-L abolishes the noncompetitive inhibition by Kc. The modification of the kinetic properties of the pumps by the antibody is highly specific in that affinities for Nac and Ko as substrates are unaffected. However, the effect of the antibody on noncompetitive inhibition by Kc does not explain the stimulation of the pump fully since there is significant stimulation at near-zero [K]c.
Authors:
P Dunham; C Anderson
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of general physiology     Volume:  90     ISSN:  0022-1295     ISO Abbreviation:  J. Gen. Physiol.     Publication Date:  1987 Jul 
Date Detail:
Created Date:  1987-10-16     Completed Date:  1987-10-16     Revised Date:  2008-11-20    
Medline Journal Info:
Nlm Unique ID:  2985110R     Medline TA:  J Gen Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  3-25     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Adenosine Triphosphate / blood
Animals
Blood Group Antigens / immunology
Erythrocytes / immunology,  metabolism*
Ion Channels / metabolism*
Isoantibodies / immunology
Kinetics
Potassium / blood*
Sheep
Sodium / blood*
Grant Support
ID/Acronym/Agency:
AM-28290/AM/NIADDK NIH HHS; AM-33640/AM/NIADDK NIH HHS
Chemical
Reg. No./Substance:
0/Blood Group Antigens; 0/Ion Channels; 0/Isoantibodies; 56-65-5/Adenosine Triphosphate; 7440-09-7/Potassium; 7440-23-5/Sodium

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Full Text
Journal Information
Journal ID (nlm-ta): J Gen Physiol
ISSN: 0022-1295
ISSN: 1540-7748
Publisher: The Rockefeller University Press
Article Information
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Print publication date: Day: 1 Month: 7 Year: 1987
Volume: 90 Issue: 1
First Page: 3 Last Page: 25
ID: 2228862
Publisher Id: 87310342
PubMed Id: 2442296

On the mechanism of stimulation of the Na/K pump of LK sheep erythrocytes by anti-L antibody


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