Junctional adhesion molecule A (JAM-A) and sialic acid (JAM-A; SA (for Sialic Acid))

Junctional adhesion molecule A (JAM-A) is a transmembrane cell surface protein belonging to the immunoglobulin superfamily, localized at tight junctions in epithelial and endothelial cells, and plays a critical role in cell-cell adhesion, permeability barrier formation, and signaling. It serves as a receptor for several viruses (e.g., reovirus), modulates leukocyte transmigration, and orchestrates intracellular signaling through interactions with scaffolding proteins. Sialic acid refers to a diverse family of terminal acidic sugars present on glycoproteins and glycolipids on the cell surface; it functions as a primary point of contact for many viral pathogens by serving as a co-receptor that enhances viral binding to primary proteinaceous receptors such as JAM-A. Viral entry, particularly by reovirus, is a multistep process requiring initial low-affinity binding to α-linked sialic acid, which stabilizes subsequent high-affinity engagement of JAM-A, triggering internalization[2][4][6][8]. Both molecules play vital roles in disease progression, cell migration, infection, and are studied both as potential therapeutic targets and as biomarkers for disease states.

Other names

CD321JAM-1F11 receptorjunctional adhesion molecule 1N-acetylneuraminic acid (Neu5Ac)Siasterminal sialic acidsSA

Viruses (e.g., reovirus) use their attachment proteins (such as σ1) to first bind sialic acid on the host surface and then engage JAM-A to facilitate cell entry and infection. JAM-A modulates signaling by recruiting scaffolding proteins (Afadin, PDZ-GEF2) that activate Rap1 GTPase, leading to changes in cell adhesion and migration.