– 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; polymorphisms in extracellular loops 4 and 5 of OmpC confer susceptibility to CdiA-EC536-mediated toxicity.