Forms pores that allow passive diffusion of small molecules across the outer membrane. (Microbial infection) Supports colicin E5 entry in the absence of its major receptor OmpF. (Microbial infection) A mixed OmpC-OmpF heterotrimer is the outer membrane receptor for toxin CdiA-EC536. Homotrimer (Probable). Forms mixed heterotrimers with OmpF; other mixed heterotrimers are also probable (PubMed:27723824). Belongs to the Gram-negative porin family.