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(Na+ + K+)‐ATPase α‐Subunit β‐Subunit cDNA nucleotide sequence Primary structure Glycopeptide Transmembrane arrangement

The complete amino acid sequence of the oligomycin sensitivity-conferring protein (OSCP) of beef-heart mitochondria is reported. The protein contains 190 amino acids and has a molecular mass of 20967. Its structure is characterized by a concentration of charged amino acids in the two terminal segments (N l-77 and C 128-190) of the protein, whereas its central region is more hydrophobic. The earlier reported homology of the protein with the d-subunit of E. coli F1, based on the terminal amino acid sequences of OSCP, is further substantiated. Amino acid sequence Oligomycin sensitivity-conferring protein Mitochondrial H+-A TPaseAmino acid residue Homology

Exposed regions of the a-and /3-subunits of membrane-bound Na+,K+-ATPase were in turn hydrolyzed with trypsin. Resistance of the p-subunit to proteolysis was shown to be due mainly to the presence of disulfide bridge(s) in the molecule. A model for the spatial organisation of the enzyme in the membrane was proposed on the basis of detailed structural analysis of extramembrane regions of both subunits.

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