High impact information on B3GNT1

• Herein we describe the isolation and functional expression of a cDNA encoding beta-1,3-N-acetylglucosaminyltransferase (iGnT), an enzyme that is essential for the formation of poly-N-acetyllactosamine [1].
• The deduced amino acid sequence indicates that this protein has a type II membrane protein topology found in almost all mammalian glycosyltransferases cloned to date. iGnT, however, differs in having the longest transmembrane domain among glycosyltransferases cloned so far [1].
• The expression of the presumed catalytic domain as a fusion protein with the IgG binding domain of protein A enabled us to demonstrate that the cDNA encodes iGnT, the enzyme responsible for the formation of GlcNAcbeta1 --> 3Galbeta1 --> 4GlcNAc --> R structure and poly-N-acetyllactosamine extension [1].
• These results, taken together, indicate that poly-N-acetyllactosamine synthesis in N-glycans and core 2- and core 4-branched O-glycans is achieved by iGnT and distinct members of the beta4Gal-T gene family [2].
• We also found that iGnT acts less efficiently on acceptors containing increasing numbers of N-acetyllactosamine repeats, in contrast to beta4Gal-TI, which exhibits no significant change [2].

Anatomical context of B3GNT1

• When the galactosylated glycoproteins in extracts of Lec8 CHO cells were incubated with UDP-[3H]GlcNAc, the endogenous iGNT quantitatively added GlcNAc in beta 1-3-linkage to terminal galactosyl residues in the leukoagglutinating phytohemagglutinin-bound glycoproteins [3].

Associations of B3GNT1 with chemical compounds

• These results demonstrate for the first time that 2,6-branched mannosyl residues are restricted to a subset of CHO glycoproteins and that the iGNT in vitro preferentially recognizes glycoproteins containing the 2,6-branched mannose determinant [3].

References