Alpha-1,3-galactosyltransferase (GGTA1) (GGTA1)

Porcine Alpha-1,3-galactosyltransferase (GGTA1) is a Golgi-resident enzyme that catalyzes the synthesis of the galactose-alpha-1,3-galactose (alpha-Gal) epitope on glycoproteins and glycolipids [3, 10]. While present in most mammals, the GGTA1 gene is inactivated in humans and Old World primates, leading to the natural production of high titers of anti-Gal antibodies [1, 13]. These antibodies recognize the alpha-Gal epitope on porcine tissues, serving as the primary barrier to xenotransplantation by triggering hyperacute rejection (HAR) [4, 8]. To overcome this, GGTA1 is a primary target for genetic knockout in donor pigs, such as the FDA-approved GalSafe pig, to ensure compatibility with the human immune system [9, 11]. Additionally, the alpha-Gal epitope is the causative agent in Alpha-gal syndrome, a tick-borne allergy to red meat and certain mammalian-derived drugs like cetuximab [17, 21]. Therapeutic interventions focus on eliminating the epitope through gene editing (e.g., CRISPR/Cas9) or enzymatic cleavage using alpha-galactosidase to improve the safety of xenografts and biological products [4, 15].

Other names

N-acetyllactosaminide alpha-1,3-galactosyltransferasealpha-1,3-GTalpha3GalTGlycoprotein alpha-galactosyltransferase 1GalactosyltransferaseGGTA1

The enzyme GGTA1 synthesizes the alpha-Gal epitope, which is the primary target of preformed human anti-Gal antibodies [1, 3]. Therapeutic strategies target this system by knocking out the GGTA1 gene to prevent epitope expression, using alpha-galactosidase to enzymatically remove the epitope from tissues, or employing decoy polymers like Gas-903 to sequester circulating anti-Gal antibodies [4, 9, 15].