Has lost the ability to synthesize Forssman glycolipid antigen (FORS1/FG) (PubMed:10506200). Might have acquired an alternative function in glycosphingolipid metabolism, but it remains to be established. It appears to have drifted more slowly than confirmed pseudogenes in the glycosyltransferase 6 family, suggesting that it has remained under evolutionary pressure. Binds 1 Mn(2+) ion per subunit. Protein modification; protein glycosylation. Widely expressed. Expressed at higher level in placenta, ovary and peripheral blood leukocyte, whereas it is weakly expressed in liver, thymus, and testis (PubMed:10506200). Expressed in bone marrow erythroid cells (PubMed:23255552). The conserved DXD motif is involved in cofactor binding. The manganese ion interacts with the beta-phosphate group of UDP and may also have a role in catalysis (By similarity). Common alleles GBGT1*01N.01 and GBGT1*01N.02 do not synthesize Forssman glycolipid antigen (FORS1). A rare allele encoding an arginine to glutamine change at residue 296 is associated with the ability to synthesize Forssman antigen, which is expressed in erythrocytes and is inheritable, thus defining a new histo-blood group FORS, also known as Apae. This variation might have arised as a consequence of the selective pressure exerted by microorganisms. For instance, the uropathogenic E.coli expressing prsG adhesin only binds and agglutinates FORS1-expressing erythrocytes. Thus, FORS1-positive individuals might be more susceptible to certain pathogens. Belongs to the glycosyltransferase 6 family. The Forssman antigen (FORS1) is normally expressed on erythrocytes of some non-primate mammals. However, in rare cases it is expressed on human erythrocytes of histo-blood group FORS carriers. Globoside alpha-1,3-N-acetylgalactosaminyltransferase 1