Sodium pump that utilizes the energy of pyrophosphate hydrolysis as the driving force for Na(+) movement across the membrane. diphosphate + H2O + Na(+)(in) = H(+) + Na(+)(out) + 2 phosphate Requires K(+) for maximal activity. Homodimer. Belongs to the H(+)-translocating pyrophosphatase (TC 3.A.10) family. K(+)-stimulated subfamily. Truncated N-terminus.