ATP synthase delta/OSCP subunit
# ATP synthase delta/OSCP subunit

ATP synthase delta subunit is a subunit of bacterial and chloroplast F-ATPase/synthase. It is known as OSCP (oligomycin sensitivity conferral protein) in mitochondrial ATPase (note that in mitochondria there is a different delta subunit, ATP synthase delta/epsilon subunit).

The OSCP/delta subunit appears to be part of the peripheral stalk that holds the $F_1$ complex alpha3beta3 catalytic core stationary against the torque of the rotating central stalk, and links subunit A of the $F_O$ complex with the $F_1$ complex. In mitochondria, the peripheral stalk consists of OSCP, as well as $F_O$ components F6, B and D. In bacteria and chloroplasts the peripheral stalks have different subunit compositions: delta and two copies of $F_O$ component B (bacteria), or delta and $F_O$ components B and B' (chloroplasts).

F-ATPases lacking this subunit generally transport sodium instead of protons. They are proposed to be called N-ATPases, since they seem to form a distinct group that is further apart from usual F-ATPases than A-ATPases are from V-ATPases.

Human delta subunit of ATP synthase is coded by gene ATP5O.

