Part of the twin-arginine translocation (Tat) system that transports large folded proteins containing a characteristic twin-arginine motif in their signal peptide across membranes. Together with TatB, TatC is part of a receptor directly interacting with Tat signal peptides. The Tat system comprises two distinct complexes: a TatABC complex, containing multiple copies of TatA, TatB and TatC subunits, and a separate TatA complex, containing only TatA subunits. Substrates initially bind to the TatABC complex, which probably triggers association of the separate TatA complex to form the active translocon. Belongs to the TatC family.