The ompA outer membrane proteins in this group all contain the ompA-like transmembrane domain at the N terminus and the conserved bacterial outer membrane protein domain at the C terminus.The outer membrane protein A of <taxon tax_id="562">Escherichia coli</taxon> (OmpA), is one of the most studied proteins in this group [<cite idref="PUB00006571"/>]. It has a multifunctional role. OmpA is required for the action of colicins K and L and for the stabilisation of mating aggregates in conjugation. It also serves as a receptor for a number of T-even like phages and can act as a porin with low permeability that allows slow penetration of small solutes [<cite idref="PUB00006249"/>]. Outer membrane protein, OmpA