Alternative titles; symbols
HGNC Approved Gene Symbol: GALNT15
Cytogenetic location: 3p25.1 Genomic coordinates (GRCh38): 3:16,174,680-16,248,224 (from NCBI)
Membrane-bound polypeptide N-acetylgalactosaminyltransferases (EC 2.4.1.41), such as GALNT15, catalyze the first step in mucin-type O-glycosylation of peptides in the Golgi apparatus. These enzymes transfer N-acetylgalactosamine (GalNAc) from UDP-GalNAc to the hydroxyl group of serine or threonine in target proteins (summary by Peng et al., 2010).
By searching an EST database for sequences similar to GALNT7 (605005), followed by PCR of a human cerebellum cDNA library, Cheng et al. (2004) cloned GALNT15. The deduced 639-amino acid type II membrane protein has an N-terminal cytoplasmic domain, followed by a transmembrane domain, a stem region, and a catalytic region that includes conserved motifs and a C-terminal lectin-like domain. Quantitative real-time PCR of 23 human tissues detected highest GALNT15 expression in placenta, small intestine, spleen, cerebral cortex, and ovary. Intermediate expression was detected in uterus, mammary gland, stomach, cerebellum, and whole brain. All other tissues showed much weaker expression, except leukocytes, which showed none.
Using recombinant human enzymes and UDP-GalNAc as sugar donor, Cheng et al. (2004) compared the catalytic activities of GALNT15 and GALNT2 (602274). The 2 enzymes exhibited distinct substrate specificities against a panel of synthetic peptide acceptor substrates. They also differed in site-specific and order-specific GalNAc incorporation. In general, GALNT15 had weaker catalytic activity than GALNT2. However, GALNT15 transferred up to 7 GalNAc residues onto a peptide derived from MUC5AC (158373), whereas GALNT2 transferred only 5.
Cheng et al. (2004) determined that the GALNT15 gene contains at least 10 exons.
By genomic sequence analysis, Cheng et al. (2004) mapped the GALNT15 gene to chromosome 3p25.
Cheng, L., Tachibana, K., Iwasaki, H., Kameyama, A., Zhang, Y., Kubota, T., Hiruma, T., Tachibana, K., Kudo, T., Guo, J.-M., Narimatsu, H. Characterization of a novel human UDP-GalNAc transferase, pp-GalNAc-T15. FEBS Lett. 566: 17-24, 2004. [PubMed: 15147861] [Full Text: https://doi.org/10.1016/j.febslet.2004.03.108]
Peng, C., Togayachi, A., Kwon, Y.-D., Xie, C., Wu, G., Zou, X., Sato, T., Ito, H., Tachibana, K., Kubota, T., Noce, T., Narimatsu, H., Zhang, Y. Identification of a novel human UDP-GalNAc transferase with unique catalytic activity and expression profile. Biochem. Biophys. Res. Commun. 402: 680-686, 2010. [PubMed: 20977886] [Full Text: https://doi.org/10.1016/j.bbrc.2010.10.084]