This is the non-catalytic component of the active enzyme, which catalyzes the hydrolysis of ATP coupled with the exchange of Na(+) and K(+) ions across the plasma membrane. The exact function of the beta-3 subunit is not known.
Subcellular locations: Apical cell membrane, Basolateral cell membrane, Melanosome
Identified by mass spectrometry in melanosome fractions from stage I to stage IV.