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