title: Revisiting the human polypeptide GalNAc-T1 and T13 paralogs.
abstract: Polypeptide GalNAc-transferases (GalNAc-Ts) constitute a family of 20 human glycosyltransferases (comprising 9 subfamilies), which initiate mucin-type O-glycosylation. The O-glycoproteome is thought to be differentially regulated via the different substrate specificities and expression patterns of each GalNAc-T isoforms. Here, we present a comprehensive in vitro analysis of the peptide substrate specificity of GalNAc-T13, showing that it essentially overlaps with the ubiquitous expressed GalNAc-T1 isoform found in the same subfamily as T13. We have also identified and partially characterized nine splice variants of GalNAc-T13, which add further complexity to the GalNAc-T family. Two variants with changes in their lectin domains were characterized by in vitro glycosylation assays, and one (Δ39Ex9) was inactive while the second one (Ex10b) had essentially unaltered activity. We used reverse transcription-polymerase chain reaction analysis of human neuroblastoma cell lines, normal brain and a small panel of neuroblastoma tumors to demonstrate that several splice variants (Ex10b, ΔEx9, ΔEx2-7 and ΔEx6/8-39bpEx9) were highly expressed in tumor cell lines compared with normal brain, although the functional implications remain to be unveiled. In summary, the GalNAc-T13 isoform is predicted to function similarly to GalNAc-T1 against peptide substrates in vivo, in contrast to a prior report, but is unique by being selectively expressed in the brain.
authors.affiliation: Laboratory of Tumor Immunology and Glycobiology, Institut Pasteur de Montevideo, Mataojo 2020 (C.P. 11400), Montevideo, Uruguay.|Departamento de Inmunobiología, Facultad de Medicina, Universidad de la República, Avenida General Flores 2125 (C.P. 11800), Montevideo, Uruguay.
authors.forename: María Florencia
authors.initials: MF
authors.lastname: Festari
authors.affiliation: Laboratory of Molecular & Structural Microbiology.
authors.forename: Felipe
authors.initials: F
authors.lastname: Trajtenberg
authors.affiliation: Laboratory of Tumor Immunology and Glycobiology, Institut Pasteur de Montevideo, Mataojo 2020 (C.P. 11400), Montevideo, Uruguay.
authors.forename: Nora
authors.initials: N
authors.lastname: Berois
authors.affiliation: Grupo de Simulaciones Biomoleculares, Institut Pasteur de Montevideo, Mataojo 2020 (C.P. 11400), Montevideo, Uruguay.
authors.forename: Sergio
authors.initials: S
authors.lastname: Pantano
authors.affiliation: Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Leslie
authors.initials: L
authors.lastname: Revoredo
authors.affiliation: Department of Cellular and Molecular Medicine and Odontology, Copenhagen Center for Glycomics, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark.
authors.forename: Yun
authors.initials: Y
authors.lastname: Kong
authors.affiliation: Laboratory of Tumor Immunology and Glycobiology, Institut Pasteur de Montevideo, Mataojo 2020 (C.P. 11400), Montevideo, Uruguay.
authors.forename: Patricia
authors.initials: P
authors.lastname: Solari-Saquieres
authors.affiliation: Department of Cellular and Molecular Medicine and Odontology, Copenhagen Center for Glycomics, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Narimatsu
authors.affiliation: Departamento de Inmunobiología, Facultad de Medicina, Universidad de la República, Avenida General Flores 2125 (C.P. 11800), Montevideo, Uruguay.
authors.forename: Teresa
authors.initials: T
authors.lastname: Freire
authors.affiliation: Unité de Chimie de Biomoleculares, CNRS UMR 3523 Institut Pasteur, Paris, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Bay
authors.affiliation: Unidad de Biología Molecular, Institut Pasteur de Montevideo, Mataojo 2020 (C.P. 11400), Montevideo, Uruguay.|Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Avenida General Flores 2125 (C.P. 11800), Montevideo, Uruguay.
authors.forename: Carlos
authors.initials: C
authors.lastname: Robello
authors.affiliation: CNRS UMR 8126, Université Paris-Sud 11, and Département de Biologie et Pathologie Médicales Institut Gustave Roussy, Villejuif Cedex, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Bénard
authors.affiliation: Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA.|Departments of Pediatrics and Biochemistry, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Gerken
authors.affiliation: Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Henrik
authors.initials: H
authors.lastname: Clausen
authors.affiliation: Laboratory of Tumor Immunology and Glycobiology, Institut Pasteur de Montevideo, Mataojo 2020 (C.P. 11400), Montevideo, Uruguay eosinaga@fmed.edu.uy.|Departamento de Inmunobiología, Facultad de Medicina, Universidad de la República, Avenida General Flores 2125 (C.P. 11800), Montevideo, Uruguay.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Osinaga
mesh_terms: D000595:Amino Acid Sequence; D001921:Brain / Q000378:metabolism; D005786:Gene Expression Regulation; D006020:Glycopeptides / Q000235:genetics* / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D037102:Lectins / Q000235:genetics / Q000378:metabolism; D017350:N-Acetylgalactosaminyltransferases / Q000235:genetics* / Q000378:metabolism; D010455:Peptides / Q000235:genetics* / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics* / Q000378:metabolism; D013379:Substrate Specificity; D000097763:Polypeptide N-acetylgalactosaminyltransferase
chemical_list: D006020:Glycopeptides; D037102:Lectins; D017350:N-Acetylgalactosaminyltransferases; D010455:Peptides; D020033:Protein Isoforms; D000097763:Polypeptide N-acetylgalactosaminyltransferase
keywords: GALNT/GALNT13/splicing/MALDI-TOF/neuroblastoma/cancer