Nongastric H+,K+-ATPase: cell biologic and functional properties
A V Grishin1, J Reinhard, L A Dunbar
1Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA.
Seminars in Nephrology
|October 8, 1999
Summary
Renal potassium transport involves H+,K+-ATPase ion pumps. Some isoforms exchange sodium for potassium, and endocytosis regulates pump activity, impacting kidney function.
Area of Science:
- Biochemistry
- Physiology
- Cell Biology
Background:
- The H+,K+-ATPase family of ion pumps plays a role in renal potassium transport.
- While isoform expression is known, functional and cell biologic attributes of these pumps are not fully understood.
- These P-type ATPases are found on the apical surfaces of tubule epithelial cells.
Purpose of the Study:
- To investigate the properties of renal H+,K+-ATPases in vitro and in situ.
- To elucidate the ion exchange mechanisms and regulatory pathways of renal H+,K+-ATPases.
Main Methods:
- In vitro and in situ studies of ion fluxes.
- Analysis of a nongastric H+,K+-ATPase isoform.
- Investigation of endocytosis regulation using transgenic mice expressing modified gastric H+,K+-ATPase beta-subunit.
Main Results:
- A nongastric H+,K+-ATPase isoform was found to exchange sodium for potassium under normal conditions.
- Renal H+,K+-ATPase activity in situ is regulated by endocytosis via a signal in the gastric H+,K+-ATPase beta-subunit's cytoplasmic tail.
- Transgenic mice lacking this endocytosis signal exhibited constitutively active renal potassium resorption.
Conclusions:
- Individual H+,K+-ATPase isoforms may contribute uniquely to renal cation transport.
- Endocytic regulation is a key mechanism controlling renal H+,K+-ATPase activity.
- Further research is needed to identify specific isoforms regulated by endocytosis and the associated cellular machinery.
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