PMID- 10409699
OWN - NLM
STAT- MEDLINE
DCOM- 19990826
LR  - 20190508
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 274
IP  - 30
DP  - 1999 Jul 23
TI  - Identification, expression, and characterization of a cDNA encoding human
      endoplasmic reticulum mannosidase I, the enzyme that catalyzes the first mannose 
      trimming step in mammalian Asn-linked oligosaccharide biosynthesis.
PG  - 21375-86
AB  - We have isolated a full-length cDNA clone encoding a human alpha1, 2-mannosidase 
      that catalyzes the first mannose trimming step in the processing of mammalian
      Asn-linked oligosaccharides. This enzyme has been proposed to regulate the timing
      of quality control glycoprotein degradation in the endoplasmic reticulum (ER) of 
      eukaryotic cells. Human expressed sequence tag clones were identified by sequence
      similarity to mammalian and yeast oligosaccharide-processing mannosidases, and
      the full-length coding region of the putative mannosidase homolog was isolated by
      a combination of 5'-rapid amplification of cDNA ends and direct polymerase chain 
      reaction from human placental cDNA. The open reading frame predicted a 663-amino 
      acid type II transmembrane polypeptide with a short cytoplasmic tail (47 amino
      acids), a single transmembrane domain (22 amino acids), and a large COOH-terminal
      catalytic domain (594 amino acids). Northern blots detected a transcript of
      approximately 2.8 kilobase pairs that was ubiquitously expressed in human
      tissues. Expression of an epitope-tagged full-length form of the human
      mannosidase homolog in normal rat kidney cells resulted in an ER pattern of
      localization. When a recombinant protein, consisting of protein A fused to the
      COOH-terminal luminal domain of the human mannosidase homolog, was expressed in
      COS cells, the fusion protein was found to cleave only a single alpha1,2-mannose 
      residue from Man(9)GlcNAc(2) to produce a unique Man(8)GlcNAc(2) isomer (Man8B). 
      The mannose cleavage reaction required divalent cations as indicated by
      inhibition with EDTA or EGTA and reversal of the inhibition by the addition of
      Ca(2+). The enzyme was also sensitive to inhibition by deoxymannojirimycin and
      kifunensine, but not swainsonine. The results on the localization, substrate
      specificity, and inhibitor profiles indicate that the cDNA reported here encodes 
      an enzyme previously designated ER mannosidase I. Enzyme reactions using a
      combination of human ER mannosidase I and recombinant Golgi mannosidase IA
      indicated that that these two enzymes are complementary in their cleavage of
      Man(9)GlcNAc(2) oligosaccharides to Man(5)GlcNAc(2).
FAU - Gonzalez, D S
AU  - Gonzalez DS
AD  - Complex Carbohydrate Research Center and the Department of Biochemistry and
      Molecular Biology, University of Georgia, Athens, Georgia 30602, USA.
FAU - Karaveg, K
AU  - Karaveg K
FAU - Vandersall-Nairn, A S
AU  - Vandersall-Nairn AS
FAU - Lal, A
AU  - Lal A
FAU - Moremen, K W
AU  - Moremen KW
LA  - eng
SI  - GENBANK/AF145732
GR  - GM47533/GM/NIGMS NIH HHS/United States
GR  - RR05351/RR/NCRR 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  - 0 (DNA, Complementary)
RN  - 0 (Oligosaccharides)
RN  - 0 (RNA, Messenger)
RN  - EC 3.2.1.- (Mannosidases)
RN  - EC 3.2.1.113 (mannosyl-oligosaccharide 1,2-alpha-mannosidase)
RN  - PHA4727WTP (Mannose)
SB  - IM
MH  - Amino Acid Sequence
MH  - Animals
MH  - Base Sequence
MH  - Catalysis
MH  - DNA, Complementary/genetics/metabolism
MH  - Endoplasmic Reticulum/*enzymology
MH  - Humans
MH  - Mannose/*metabolism
MH  - Mannosidases/*genetics/*metabolism
MH  - Molecular Sequence Data
MH  - Oligosaccharides/biosynthesis
MH  - Open Reading Frames/genetics
MH  - RNA, Messenger/analysis/genetics
MH  - Rats
MH  - Sequence Alignment
EDAT- 1999/07/20 00:00
MHDA- 1999/07/20 00:01
CRDT- 1999/07/20 00:00
PHST- 1999/07/20 00:00 [pubmed]
PHST- 1999/07/20 00:01 [medline]
PHST- 1999/07/20 00:00 [entrez]
AID - 10.1074/jbc.274.30.21375 [doi]
PST - ppublish
SO  - J Biol Chem. 1999 Jul 23;274(30):21375-86. doi: 10.1074/jbc.274.30.21375.