Molecular cloning of a novel human UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase, GalNAc-T8, and analysis as a candidate autosomal dominant hypophosphatemic rickets (ADHR) gene.
The UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase (ppGaNTase) family of enzymes initiates mucin-like O-glycosylation of specific proteins. Using exon-prediction analysis on genomic sequence from human chromosome 12p13.3, we identified novel exons that shared significant homology with the ppGaNTases. cDNA library screening and RT-PCR produced the complete coding sequence of a novel human ppGaNTase family member, designated GalNAc-T8. The open reading frame (ORF) of GalNAc-T8 codes for a 637 amino acid, type-II membrane protein that is 45-60% identical to the other mammalian ppGaNTases. GalNAc-T8 shares high homology within the functional regions of the known ppGaNTases; however, the enzyme possesses a novel residue substitution within a characteristic motif of the catalytic domain. Northern analysis of multiple human tissue mRNAs demonstrated that the 5.0 and 2.1kb GalNAc-T8 transcripts are widely expressed. The metabolic disorder autosomal dominant hypophosphatemic rickets (ADHR) was previously mapped to the region of chromosome 12p13.3 in which GalNAc-T8 resides. Using a positional-candidate strategy for identifying the ADHR gene, GalNAc-T8 was subjected to mutational analysis in DNA from ADHR individuals. We detected multiple polymorphisms in the human GalNAc-T8 ORF, but did not find ADHR mutations. In summary, these studies identified the human GalNAc-T8 gene, as well as multiple genomic polymorphisms that will be useful for further understanding the structure-function relations of the ppGaNTases.
White
K E
KE
Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Lorenz
B
B
Evans
W E
WE
Meitinger
T
T
Strom
T M
TM
Econs
M J
MJ
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001483:Base Sequence; D015152:Blotting, Northern; D020134:Catalytic Domain; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry / Q000235:genetics; D004252:DNA Mutational Analysis; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D005091:Exons; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D005796:Genes / Q000235:genetics; D005799:Genes, Dominant / Q000235:genetics*; D006801:Humans; D007015:Hypophosphatemia, Familial / Q000201:enzymology / Q000235:genetics*; D007438:Introns; D008969:Molecular Sequence Data; D009154:Mutation; D017350:N-Acetylgalactosaminyltransferases / Q000235:genetics*; D011110:Polymorphism, Genetic; D018807:Polymorphism, Single-Stranded Conformational; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D000097763:Polypeptide N-acetylgalactosaminyltransferase
D004247:DNA; D018076:DNA, Complementary; D017350:N-Acetylgalactosaminyltransferases; D012333:RNA, Messenger; D000097763:Polypeptide N-acetylgalactosaminyltransferase