IPAC

ipaC refers most commonly to a virulence-associated protein in certain pathogenic bacteria, notably Shigella species. The ipaC gene is part of the invasion plasmid antigen (ipa) region carried on the Shigella virulence plasmid and is often co-located with other ipa genes such as ipaB and ipaD. The protein is secreted by the bacterial type III secretion system and works in concert with IpaB to form a translocon pore in the host cell membrane. This pore enables the delivery of bacterial effector proteins into the host cell and facilitates cellular entry, contributing to cytoskeletal rearrangements that promote bacterial uptake.

Function and role in disease: IpaC is essential for efficient invasion of epithelial cells and plays a key role in the pathogenesis of bacillary dysentery (shigellosis). By interacting with host cell signaling and cytoskeletal components, IpaC helps reorganize actin and membrane structures, aiding bacterial internalization and dissemination. The protein is a focus of research aimed at understanding the mechanics of type III secretion–mediated invasion and at developing antivirulence strategies or vaccines that target the invasion process.

Structure and regulation: Detailed structural information continues to emerge from microbiology studies. IpaC is expressed under conditions that mimic the intracellular environment and is regulated as part of the broader ipa operon on the virulence plasmid. While the term ipaC is most closely associated with Shigella, some related enteric pathogens possess functionally similar proteins.

In other contexts, ipaC is not widely established as a distinct, widely used term outside microbiology.