OmpA function as a receptor for various amino acids and peptide and for F-pili. Various other receptors are identified for nucleoside,vitamins and other nutrients. Lipoprotein stabilizes OM structure. The lipid end of the molecule is embedded in the lipid area of OM,while the protein end is covalently bound to murein. A lipoprotein in a plant pathogenic bacterium,Erwinia has pectin methylesterase activity.
Like other microbes,many gram-negative bacteria can use polymers as their carbon and energy sources 7.1 and excrete hydrolyzing enzymes into their external environment. The OM has protein responsible for the translocation of extracellular proteins 3.8.2. Cytochromes and ferric reductase are located in the OM in Fe-reducing bacteria such as shewanella and geobacter