E. coli has two major porins located in the outer membrane. The function of porins is the

E. coli has two major porins, OMP C and OMP E (OMP is outer-membrane protein). A porin is a protein trimer with each subunit containing a pore with a diameter of 1 nm. Porins function in outer-membrane (OM) permeability. While porins are known to permit the transfer of small molecules across the OM, specific porins may also influence the diffusion of layer molecules. Depending on charge, porins may also repel certain molecules, such as bile salts found in the intestinal environment.