Part of the anaerobic respiratory chain of trimethylamine-N-oxide reductase TorA. Acts by transferring electrons from the membranous menaquinones to TorA. This transfer probably involves an electron transfer pathway from menaquinones to the N-terminal domain of TorC, then from the N-terminus to the C-terminus, and finally to TorA. TorC apocytochrome negatively autoregulates the torCAD operon probably by inhibiting the TorS kinase activity (By similarity). The N-terminal domain interacts with TorA. The immature C-terminal domain can bind to the N-terminal detector region of TorS (By similarity). Binds 5 heme groups per subunit. Belongs to the TorC/TorY family.