Low-potential cytochrome c that plays a role in the oxygen-evolving complex of photosystem II. Binds 1 heme c group covalently per subunit (PubMed:11478889). E(0) is -260 mV. The cyanobacterial oxygen-evolving complex is composed of PsbO, PsbP, PsbQ, PsbV and PsbU (Potential). Homodimer in crystal structure (PubMed:11478889). Associated with photosystem II at the lumenal side of the thylakoid membrane. Belongs to the cytochrome c family. PsbV subfamily.