ATP synthase (proton-translocating ATPase) (EC 3.6.3.14) [1,2] is a component of the cytoplasmic membrane of eubacteria, the inner membrane of mitochondria, and the thylakoid membrane of chloroplasts. The ATPase complex is composed of an oligomeric transmembrane sector, called CF(0), and a catalytic core, called coupling factor CF(1). The former acts as a proton channel; the latter is composed of five subunits, α, β, γ, delta and epsilon. Subunit γ is believed to be important in regulating ATPase activity and the flow of protons through the CF(0) complex. The best conserved region of the γ subunit [3] is its C-terminus which seems to be essential for assembly and catalysis. As a signature pattern to detect ATPase γ subunits, we used a 14 residue conserved segment where the last amino acid is found one to three residues from the C-terminal extremity.