Abstract
The mechanisms involved in receptor-mediated inhibition of Na+ -K+ - ATPase remain poorly understood. In this study, we evaluate whether inhibition of proximal tubule Na+ -K+ -ATPase activity by dopamine is linked to its removal from the plasma membrane and internalization into defined intracellular compartments. Clathrin-coated vesicles were isolated by sucrose gradient centrifugation and negative lectin selection, and early and late endosomes were separated on a flotation gradient. Inhibition of Na+- K+-ATPase activity by dopamine, in contrast to its inhibition by ouabain, was accompanied by a sequential increase in the abundance of the α-subunit in clathrin-coated vesicles (1 min), early endosomes (2.5 min), and late endosomes (5 min), suggesting its stepwise translocation between these organelles. A similar pattern was found for the β-subunit. The increased incorporation of both subunits in all compartments was blocked by calphostin C. The results demonstrate that the dopamine-induced decrease in Na+- K+ATPase activity in proximal tubules is associated with internalization of its α- and β-subunits into early and late endosomes via a clathrin- dependent pathway and that this process is protein kinase C dependent. The presence of Na+-K+ATPase subunits in endosomes suggests that these compartments may constitute normal traffic reservoirs during pump degradation and/or synthesis.
Original language | English (US) |
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Pages (from-to) | C1458-C1465 |
Journal | American Journal of Physiology - Cell Physiology |
Volume | 273 |
Issue number | 5 42-5 |
DOIs | |
State | Published - 1997 |
Keywords
- Actin-microtubule cytoskeleton
- Clathrin vesicles
- Dopamine
- Endosomes
- Protein kinase C
- Proximal tubules
ASJC Scopus subject areas
- Clinical Biochemistry
- Cell Biology
- Physiology
- Physiology (medical)