Outer membrane protein C (OmpK36) (OmpC)

Outer membrane protein C, specifically known as OmpK36 in Klebsiella pneumoniae, is a major non-specific porin that forms a trimeric beta-barrel structure in the bacterial outer membrane. It functions as a critical conduit for the passive diffusion of small hydrophilic molecules, including essential nutrients and various classes of antibiotics such as carbapenems and cephalosporins. In the context of clinical pathology, OmpK36 is a primary determinant of antibiotic susceptibility; its downregulation or structural modification is a hallmark of carbapenem-resistant Enterobacteriaceae (CRE). Mutations that constrict the porin channel or the complete loss of the protein significantly limit the intracellular concentration of drugs, often working in tandem with beta-lactamase production to confer high-level resistance. Consequently, OmpK36 is a focal point for studying bacterial permeability and developing next-generation antibiotics designed to bypass or utilize these entry ports more effectively.

Other names

OmpK36Porin OmpCOuter membrane protein K36OmpK36 porin

OmpK36 acts as a non-specific aqueous channel that allows the passive diffusion of hydrophilic antibiotics, such as carbapenems and cephalosporins, across the outer membrane of Klebsiella pneumoniae to reach their targets in the periplasm. Resistance is often mediated by the loss of this porin or mutations that narrow the channel pore, thereby reducing drug entry.