Antigen X
Short name=AGX
Sperm-associated antigen 2
Including the following 2 domains:
UDP-N-acetylgalactosamine pyrophosphorylase
EC=2.7.7.-
Alternative name(s):
AGX-1
UDP-N-acetylglucosamine pyrophosphorylase
EC=2.7.7.23
Alternative name(s):
AGX-2
Function
Converts UDP and GlcNAc-1-P into UDP-GlcNAc, and UDP and GalNAc-1-P into UDP-GalNAc. Isoform AGX1 has 2 to 3 times higher activity towards GalNAc-1-P, while isoform AGX2 has 8 times more activity towards GlcNAc-1-P.
Catalytic activity
UTP + N-acetyl-alpha-D-glucosamine 1-phosphate = diphosphate + UDP-N-acetyl-D-glucosamine.
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.
Subunit structure
Monomer and homodimer. Isoform AGX1 is a homodimer. Isoform AGX2 is a monomer.
Subcellular location
Cytoplasm. Note: 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.
Tissue specificity
Widely expressed. Isoform AGX1 is more abundant in testis than isoform AGX2, while isoform AGX2 is more abundant than isoform AGX1 in somatic tissue. Expressed at low level in placenta, muscle and liver.
Sequence similarities
Belongs to the UDPGP type 1 family.
