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).

ATP synthase delta (OSCP) subunit
Structure of the N-terminal domain of the delta subunit of the E. coli ATPsynthase.[1]
Identifiers
Symbol	OSCP
Pfam	PF00213
InterPro	IPR000711
PROSITE	PDOC00327
SCOP2	1abv / SCOPe / SUPFAM
TCDB	3.A.2
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary PDB 2a7uB:7-135 1abv :7-106 2bo5A:37-143

The OSCP/delta subunit appears to be part of the peripheral stalk that holds the F₁ complex α3β3 catalytic core stationary against the torque of the rotating central stalk, and links subunit A of the F_O complex with the F₁ 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).^[2]

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.^[3]

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