Subfamily of Glycosyltransferase Family GT2 of unknown function. GT-2 includes diverse families of glycosyltransferases with a common GT-A type structural fold, which has two tightly associated beta/alpha/beta domains that tend to form a continuous central sheet of at least eight beta-strands. These are enzymes that catalyze the transfer of sugar moieties from activated donor molecules to specific acceptor molecules, forming glycosidic bonds. Glycosyltransferases have been classified into more than 90 distinct sequence based families.

hopanoid biosynthesis associated glycosyl transferase protein HpnI. This family of genes include a glycosyl transferase, group 2 domain (pfam00535) which are responsible, generally for the transfer of nucleotide-diphosphate sugars to substrates such as polysaccharides and lipids. The member of this clade from Acidithiobacillus ferrooxidans ATCC 23270 (AFE_0974) is found in the same locus as squalene-hopene cyclase (SHC, TIGR01507) and other genes associated with the biosynthesis of hopanoid natural products. Similarly, in Ralstonia eutropha JMP134 (Reut_B4902) this gene is adjacent to HpnAB, IspH and HpnH (TIGR03470), although SHC itself is elsewhere in the genome. Notably, this gene (here named HpnI) and three others form a conserved set (HpnIJKL) which occur in a subset of all genomes containing the SHC enzyme. This relationship was discerned using the method of partial phylogenetic profiling. This group includes Zymomonas mobilis, the organism where the initial hopanoid biosynthesis locus was described consisting of the genes HpnA-E and SHC (HpnF). Continuing past SHC are found a phosphorylase enzyme (ZMO0873, i.e. HpnG, TIGR03468) and another radical SAM enzyme (ZMO0874), HpnH. Although discontinuous in Z. mobilis, we continue the gene symbol sequence with HpnIJKL. Hopanoids are known to feature polar glycosyl head groups in many organisms.

Glycosyltransferases, probably involved in cell wall biogenesis [Cell envelope biogenesis, outer membrane]

Glycosyl transferase family 21. This is a family of ceramide beta-glucosyltransferases - EC:2.4.1.80.

Glucosylceramide synthase catalyzes the first glycosylation step of glycosphingolipid synthesis. UDP-glucose:N-acylsphingosine D-glucosyltransferase (glucosylceramide synthase or ceramide glucosyltransferase) catalyzes the first glycosylation step of glycosphingolipid synthesis. Its product, glucosylceramide, serves as the core of more than 300 glycosphingolipids (GSL). GSLs are a group of membrane components that have the lipid portion embedded in the outer plasma membrane leaflet and the sugar chains extended to the outer environment. Several lines of evidence suggest the importance of GSLs in various cellular processes such as differentiation, adhesion, proliferation, and cell-cell recognition. In pathogenic fungus Cryptococcus neoformans, glucosylceramide serves as an antigen that elicits an antibody response in patients and it is essential for fungal growth in host extracellular environment.