The isolated H4-H5 cytoplasmic loop of Na,K-ATPase overexpressed in Escherichia coli retains its ability to bind ATP.
The H4-H5 loop of the alpha-subunit of mouse brain Na,K-ATPase was expressed and isolated from E.coli cells. Using fluorescence analogues of ATP, this loop was shown to retain its capability to bind ATP. Isolation of a soluble H4-H5 loop with the native ATP binding site is a critical step for detailed studies of the molecular mechanism of ATP binding and utilisation.