FRET analysis reveals a critical conformational change within the Na,K-ATPase α1 subunit N-terminus during GPCR-dependent endocytosis

Dopamine is a major regulator of sodium reabsorption in proximal tubule epithelia. It induces the endocytosis of plasma membrane Na,K-ATPase molecules, and this results in a reduced capacity of the cells to transport sodium. Dopamine induces the phosphorylation of Ser-18 in the α1-subunit of Na,K-ATPase. Fluorescence resonance energy transfer analysis of cells expressing YFP-α1 and β1-CFP reveals that treatment of the cells with dopamine increases energy transfer between CFP and YFP. This is consistent with a protein conformational change that results in the N-terminal end of α1 moving closer to the internal face of the plasma membrane.