Outer membrane protein C (OmpC) (OmpC)

Outer membrane protein C (OmpC) is a major porin found in the outer membrane of Gram-negative bacteria, such as Escherichia coli and Salmonella species. It forms a trimeric beta-barrel structure that functions as a non-specific aqueous channel, allowing the passive diffusion of small hydrophilic molecules, including essential nutrients and various classes of antibiotics like beta-lactams and fluoroquinolones (UniProt P06996). OmpC expression is tightly regulated by environmental osmolarity via the EnvZ/OmpR two-component system, typically increasing in high-osmolarity conditions to maintain cellular homeostasis (PubMed: 25233374). In the context of infectious diseases, OmpC is a critical determinant of antibiotic susceptibility; mutations, reduced expression, or porin switching are frequently associated with the development of multi-drug resistance in clinical isolates (PubMed: 28439033). Furthermore, OmpC serves as a significant antigen in the human immune response, where the presence of anti-OmpC antibodies is utilized as a diagnostic biomarker for inflammatory bowel diseases, specifically helping to differentiate Crohn's disease from ulcerative colitis (PubMed: 11246362).

Other names

Porin COuter membrane porin COmpC porinOmp2

OmpC acts as a passive diffusion channel that facilitates the entry of hydrophilic antibiotics into the periplasmic space of Gram-negative bacteria. While not typically inhibited by drugs, its presence and pore size determine the intracellular concentration and efficacy of various antimicrobial agents.