Component of the type III secretion system (T3SS), also called injectisome, which is used to inject bacterial effector proteins into eukaryotic host cells. Forms a ring-shaped multimeric structure with an apparent central pore in the outer membrane (By similarity). Necessary for both basic pathogenicity and the induction of the hypersensitive response in resistant plants (PubMed:1472717). The core secretion machinery of the T3SS is composed of approximately 20 different proteins, including cytoplasmic components, a base, an export apparatus and a needle. This subunit is part of the base, which anchors the injectisome in the bacterial cell envelope. Forms a stable homooligomeric complex. Belongs to the bacterial secretin family. T3SS SctC subfamily.