Integrin alpha-9 (ITGA9)

Integrin alpha‑9 is a transmembrane glycoprotein encoded by the *ITGA9* gene located at chromosome 3p22.2. It forms a heterodimer with beta‑1 subunit to create the α9β1 integrin receptor complex. This receptor mediates both cell–cell and cell–matrix adhesions by binding extracellular matrix ligands such as tenascin-C, VCAM1, osteopontin, extra domain A fibronectin, ADAMs proteins, EMELIN1, VEGF, cytotactin (SVEP1/polydom), among others. Unlike many other integrins it does not recognize classic RGD motifs but binds distinct peptide sequences within its ligands. Integrins like α9β1 play crucial roles in physiological processes including embryonic development (especially lymphatic valve formation), immune response regulation via neutrophil development/migration control, vascular smooth muscle contraction regulation through calcium signaling pathways suppression via SVEP1 interaction—and pathological processes such as tumor progression/metastasis where overexpression has been observed. The protein consists of an N-terminal extracellular domain responsible for ligand binding (~1035 amino acids), a single-pass transmembrane segment and a short C-terminal cytoplasmic tail involved in intracellular signaling interactions. Due to its involvement across multiple biological systems—including cardiovascular health/disease states and cancer—integrin alpha‑9 is considered an emerging therapeutic target with ongoing research into specific inhibitors or modulators for clinical use.

Other names

Integrin alpha-RLCITGA4LRLCintegrin subunit alpha 9

Potential mechanisms include inhibition or modulation of cell adhesion and migration by blocking ligand binding to the α9β1 integrin complex; this may affect tumor progression, inflammation, or tissue remodeling. Specific mechanisms depend on the drug candidate but generally involve antagonism or modulation of integrin-ligand interactions.