UAP1
Function
Catalyzes the last step in biosynthesis of uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) by converting UTP and glucosamine 1-phosphate (GlcNAc-1-P) to the sugar nucleotide (PubMed:9603950, PubMed:9765219). Also converts UTP and galactosamine 1-phosphate (GalNAc-1-P) into uridine diphosphate-N-acetylgalactosamine (UDP-GalNAc) (PubMed:9765219). In addition to its role in metabolism, acts as a regulator of innate immunity in response to virus infection by mediating pyrophosphorylation of IRF3: catalyzes pyrophosphorylation of IRF3 phosphorylated at 'Ser-386' by TBK1, promoting IRF3 dimerization and activation, leading to type I interferon responses (PubMed:36603579).
Isoform AGX1
Isoform AGX1 has 2 to 3 times higher activity towards galactosamine 1-phosphate (GalNAc-1-P).
Isoform AGX1
Isoform AGX2 has 8 times more activity towards glucosamine 1-phosphate (GlcNAc-1-P).
Pathway
Nucleotide-sugar biosynthesis; UDP-N-acetyl-alpha-D-glucosamine biosynthesis; UDP-N-acetyl-alpha-D-glucosamine from N-acetyl-alpha-D-glucosamine 1-phosphate: step 1/1.
Sequence Similarities
Belongs to the UDPGP type 1 family.
Tissue Specificity
Widely expressed (PubMed:8025165). Expressed at low level in placenta, muscle and liver (PubMed:8025165).
Isoform AGX1
Isoform AGX1 is more abundant in testis than isoform AGX2, while isoform AGX2 is more abundant than isoform AGX1 in somatic tissue.
Isoform AGX2
Isoform AGX2 is more abundant than isoform AGX1 in somatic tissue.
Cellular localization
- Cytoplasm
- Cytosol
- In spermatozoa, localized to the principal piece of the tail, the neck region of the head and to a lesser extent, the midpiece of the tail.
Alternative names
SPAG2, UAP1, UDP-N-acetylhexosamine pyrophosphorylase, Antigen X, Protein-pyrophosphorylation enzyme, Sperm-associated antigen 2, UDP-N-acetylgalactosamine pyrophosphorylase, UDP-N-acetylglucosamine pyrophosphorylase, AGX