Koreseptors

Koreseptors, or coreceptors, are cell-surface proteins that work in conjunction with a primary receptor to modulate ligand binding, receptor activation, or downstream signaling. They usually do not initiate signaling on their own but enhance the affinity, specificity, or kinetics of the receptor complex.

In virology, coreceptors are well known for enabling entry of certain pathogens. For example, HIV-1 uses CD4 as the primary receptor and requires a chemokine coreceptor, typically CCR5 or CXCR4, to gain entry into host cells. Genetic variation in these coreceptors can influence susceptibility to infection; the CCR5-Δ32 mutation provides resistance to many HIV-1 strains. Pharmacological inhibitors that block coreceptor function, such as CCR5 antagonists, are used as antiviral therapies.

Coreceptors also function in normal physiology by shaping signaling events in development, immune responses, and tissue remodeling. They can present or stabilize ligands for their primary receptors, promote receptor clustering, or recruit intracellular signaling partners that modulate the strength or duration of a signal. Examples include proteoglycans that act as co-receptors for growth factors and some adhesion molecules that influence receptor activity.

The concept of coreceptors extends beyond viral entry and growth factor signaling to encompass a variety of membrane proteins that influence receptor behavior. Their activity can affect disease processes, including infection, cancer, and inflammatory disorders, making them a focus of research and potential therapeutic targeting.