The frequency-domain method reveals the dimeric structure of Na,K-ATPase.

Lucifer yellow and lissamine rhodamine sulfonyl hydrazine were used as the donor and the receptor, respectively, for Förster energy transfer measurements to determine the location of the β subunit in the native Na,K-ATPase from pig kidney. It was found that (1) the β subunits are located in one functional complex, i.e., the dimer (αβ)2 appears to be the functional complex of Na,K-ATPase, and (2) the β subunits in the functional enzyme complex in the membrane are not located next to each other but are rather well separated. The distance between fluorophores covalently attached to the β subunits was found to be 5.3 nm.