ATP synthase subunit d, also known as ATP5H, is a 161 amino acid protein that belongs to the ATPase d subunit family. ATP5H encodes the d subunit of the F0 complex. ATP5H produces ATP from ADP in the presence of a proton gradient across the membrane, which is generated by electron transport complexes of the respiratory chain. Localizing to mitochondrial inner membrane, ATP5H exists as two alternatively spliced isoforms and is encoded by a gene that maps to human chromosome 17q25.1. Recombinant human ATP5H protein, fused to His-tag at N-terminus, was expressed in E.coli.