GGTA1: Glycoprotein Alpha-Galactosyltransferase 1
Key enzyme in xenotransplantation and alpha-Gal epitope synthesis
Gene Information Card
| Symbol | GGTA1 |
|---|---|
| Full Name | Glycoprotein Alpha-Galactosyltransferase 1 |
| Gene Type | Protein coding |
| Chromosomal Location | 9q33.2 |
| NCBI Gene ID | 2681 ncbi.nlm.nih.gov/gene/2681 |
| Ensembl ID | ENSG00000107175 |
| UniProt ID | Q9UKM9 |
| OMIM ID | 104030 |
| HGNC ID | 4242 |
| Aliases | GGTA1P, GGT, GGT1, GGTB, GGTB1, alpha-1,3-galactosyltransferase |
Description
GGTA1 encodes glycoprotein alpha-galactosyltransferase 1, an enzyme that catalyzes the transfer of galactose to glycoproteins and glycolipids, forming the alpha-Gal epitope (Galα1-3Galβ1-4GlcNAc-R). This epitope is a major xenoantigen responsible for hyperacute rejection in xenotransplantation. The gene is pseudogenized in humans and Old World primates due to inactivating mutations, but is functional in other mammals.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Xenotransplantation rejection (hyperacute) | Expression of alpha-Gal epitope on pig organs triggers human pre-existing anti-Gal antibodies, leading to complement-mediated rejection. | PMID: 12668987, NCBI Gene |
| Alpha-Gal syndrome (possible modifier) | Loss of GGTA1 function in humans is normal; however, dietary or environmental exposure to alpha-Gal can induce IgE-mediated delayed anaphylaxis. | ClinVar, OMIM |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 0.0 | Not detected |
| Kidney | 0.0 | Not detected |
| Heart | 0.0 | Not detected |
| Brain | 0.0 | Not detected |
| Testis | 0.0 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK293 | 0.0 | No endogenous expression (human) - pseudogene |
| HeLa | 0.0 | No endogenous expression (human) - pseudogene |
| Porcine aortic endothelial cells | High | Functional in pig cells; source of alpha-Gal epitope |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.100C>T (p.Arg34*) | Nonsense | 100% in humans | Loss of function; pseudogenization |
| c.684delG | Frameshift | 100% in humans | Loss of function; pseudogenization |
| c.808T>A (p.Tyr270Asn) | Missense | 100% in humans | Loss of function; pseudogenization |
Mutation functional classification
Loss of Function (LOF)
All reported human GGTA1 variants are loss-of-function due to pseudogenization; no functional enzyme produced.
Gain of Function (GOF)
Not reported in humans; gain-of-function variants are not observed.
Dominant Negative (DN)
Not applicable; gene is pseudogenized in humans.
View complete mutation data：
Gene Ontology (GO)
| • galactosyltransferase activity (GO:0008378) | • protein glycosylation (GO:0006486) |
| • integral component of membrane (GO:0016021) | • Golgi apparatus (GO:0005794) |
Pathways
• Glycosphingolipid biosynthesis - lacto and neolacto series (KEGG: hsa00601)
• Metabolism of carbohydrates (Reactome: R-HSA-71387)
Protein Summary
GGTA1 is a type II transmembrane glycoprotein localized to the Golgi apparatus. It catalyzes the addition of an alpha-1,3-linked galactose to N-acetyllactosamine residues, generating the Galα1-3Galβ1-4GlcNAc-R (alpha-Gal) epitope. In humans, the gene is a pseudogene due to two inactivating mutations (nonsense and frameshift), resulting in no functional protein. The enzyme is active in most mammals, making it a key target for genetic knockout in pigs to prevent hyperacute rejection in xenotransplantation.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| GGTA1 Knockout HEK293 Cell Line | EDJ-KQ4704 | Human | 2681 | Details Get a Quote |
| GGTA1 Knockout A-549 Cell Line | EDJ-KQ26177 | Human | 2681 | Details Get a Quote |
| GGTA1 Knockout HCT 116 Cell Line | EDJ-KQ27418 | Human | 2681 | Details Get a Quote |
| GGTA1 Knockout HeLa Cell Line | EDJ-KQ27419 | Human | 2681 | Details Get a Quote |
