PMID- 10037781
OWN - NLM
STAT- MEDLINE
DCOM- 19990330
LR  - 20210209
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 274
IP  - 10
DP  - 1999 Mar 5
TI  - Structure-function analysis of the UDP-N-acetyl-D-galactosamine:polypeptide
      N-acetylgalactosaminyltransferase. Essential residues lie in a predicted active
      site cleft resembling a lactose repressor fold.
PG  - 6797-803
AB  - Mucin-type O-glycosylation is initiated by a family of UDP-GalNAc:polypeptide
      N-acetylgalactosaminyltransferases (ppGaNTases). Based on sequence relationships 
      with divergent proteins, the ppGaNTases can be subdivided into three putative
      domains: each putative domain contains a characteristic sequence motif. The
      112-amino acid glycosyltransferase 1 (GT1) motif represents the first half of the
      catalytic unit and contains a short aspartate-any residue-histidine (DXH) or
      aspartate-any residue-aspartate (DXD)-like sequence. Secondary structure
      predictions and structural threading suggest that the GT1 motif forms a
      5-stranded parallel beta-sheet flanked by 4 alpha-helices, which resembles the
      first domain of the lactose repressor. Four invariant carboxylates and a
      histidine residue are predicted to lie at the C-terminal end of three
      beta-strands and line the active site cleft. Site-directed mutagenesis of murine 
      ppGaNTase-T1 reveals that conservative mutations at these 5 positions result in
      products with no detectable enzyme activity (D156Q, D209N, and H211D) or <1%
      activity (E127Q and E213Q). The second half of the catalytic unit contains a
      DXXXXXWGGENXE motif (positions 310-322) which is also found in
      beta1,4-galactosyltransferases (termed the Gal/GalNAc-T motif). Mutants of
      carboxylates within this motif express either no detectable activity, 1% or 2%
      activity (E319Q, E322Q, and D310N, respectively). Mutagenesis of highly conserved
      (but not invariant) carboxylates produces only modest alterations in enzyme
      activity. Mutations in the C-terminal 128-amino acid ricin-like lectin motif do
      not alter the enzyme's catalytic properties.
FAU - Hagen, F K
AU  - Hagen FK
AD  - Center for Oral Biology, Rochester Institute of Biomedical Sciences, University
      of Rochester, Rochester, New York 14642, USA.
FAU - Hazes, B
AU  - Hazes B
FAU - Raffo, R
AU  - Raffo R
FAU - deSa, D
AU  - deSa D
FAU - Tabak, L A
AU  - Tabak LA
LA  - eng
GR  - DE08108/DE/NIDCR NIH HHS/United States
GR  - T35 DE07189/DE/NIDCR NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - EC 2.4.1.- (N-Acetylgalactosaminyltransferases)
RN  - J2B2A4N98G (Lactose)
SB  - IM
MH  - Amino Acid Sequence
MH  - Animals
MH  - Humans
MH  - Lactose
MH  - Mice
MH  - Molecular Sequence Data
MH  - Mutagenesis, Site-Directed
MH  - N-Acetylgalactosaminyltransferases/*chemistry/genetics/metabolism
MH  - *Protein Conformation
MH  - Sequence Analysis
MH  - Structure-Activity Relationship
EDAT- 1999/02/26 00:00
MHDA- 1999/02/26 00:01
CRDT- 1999/02/26 00:00
PHST- 1999/02/26 00:00 [pubmed]
PHST- 1999/02/26 00:01 [medline]
PHST- 1999/02/26 00:00 [entrez]
AID - 10.1074/jbc.274.10.6797 [doi]
AID - S0021-9258(19)87650-0 [pii]
PST - ppublish
SO  - J Biol Chem. 1999 Mar 5;274(10):6797-803. doi: 10.1074/jbc.274.10.6797.