High impact information on GALNT4

• O-Glycan attachment to selected sites, most notably two sites in the MUC1 tandem repeat, is entirely dependent on the glycosylation-dependent function of GalNAc-T4 [1].
• Here we present data that a putative lectin domain found in the C terminus of GalNAc-T4 functions as a GalNAc lectin and confers its glycopeptide specificity [1].
• A single amino acid substitution in the lectin domain of a secreted form of GalNAc-T4 selectively blocked GalNAc-glycopeptide activity, while the general activity to peptides exerted by this enzyme was unaffected [1].
• A fourth human UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase, designated GalNAc-T4, was cloned and expressed [2].
• The function of GalNAc-T4 complements other GalNAc-transferases in O-glycosylation of MUC1 showing that glycosylation of MUC1 is a highly ordered process and changes in the repertoire or topology of GalNAc-transferases will result in altered pattern of O-glycan attachments [2].

Biological context of GALNT4

• GalNAc-T4 was placed at human chromosome 12q21.3-q22 by in situ hybridization and linkage analysis [2].
• GalNAc-T4 expressed in Sf9 cells or in a stably transfected Chinese hamster ovary cell line exhibited a unique acceptor substrate specificity [2].
• The genomic organization of GalNAc-T4 is distinct from GalNAc-T1, -T2, and -T3, which contain multiple coding exons, in that the coding region is contained in a single exon [2].

Anatomical context of GALNT4

• The GalNAc-T4 isoenzyme was found in the apical cell layers, whereas GalNAc-T2 was found in the supranuclear region of the basal cell layers of both cornea and conjunctiva [3].

Associations of GALNT4 with chemical compounds

• Furthermore, GalNAc-T4 showed the best kinetic properties with an O-glycosylation site in the P-selectin glycoprotein ligand-1 molecule [2].
• Coexpression of the human polypeptide-GalNAc-T4 transferase with MUC1(1.7TR)-IgG2a increased the glycan occupancy at Thr in PDTR, Ser in VTSA, and Ser in GSTA, supporting the function of GalNAc-T4 proposed from previous in vitro studies [4].

References