PMID- 1655786
OWN - NLM
STAT- MEDLINE
DCOM- 19911114
LR  - 20210210
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 266
IP  - 29
DP  - 1991 Oct 15
TI  - Expression of mouse mammary tumor virus glycoprotein truncations defines roles 
      for the transmembrane domain and ectodomain hydrophobic region in constitutive 
      exocytic trafficking and proteolytic processing.
PG  - 19384-95
AB  - A mutational analysis was used to identify structural domains that are important 
      for exocytic transport and proteolytic cleavage of the mouse mammary tumor virus 
      (MMTV) glycoprotein, which is expressed as a multidomain polyprotein. Rat HTC 
      hepatoma cells were transfected with the MMTV glycoprotein gene driven by the 
      constitutive Rous sarcoma virus promoter, with mutant genes encoding a series of 
      polypeptide truncations or with a defective MMTV provirus containing a premature 
      termination codon in the viral glycoprotein gene. Efficient proteolytic 
      maturation and transport of MMTV glycoproteins to the cell surface or 
      extracellular environment required the presence of the transmembrane domain but 
      not the cytoplasmic tail. Two stable truncations retaining the hydrophobic region 
      of the ectodomain in the absence of the transmembrane domain and cytoplasmic tail 
      (trgp67 and trgp58) remained in endoglycosidase H sensitive and uncleaved forms. 
      One of these truncations, trgp58, appeared to be tightly associated with 
      intracellular membranes and strongly bound by heavy chain binding protein, 
      whereas the other truncation, trgp67, was a soluble component of the lumen and 
      persists intracellularly by a heavy chain binding protein-independent pathway. 
      The truncated MMTV glycoprotein additionally lacking the hydrophobic region of 
      the ectodomain was efficiently secreted. Taken together, our results demonstrate 
      that the hydrophobic transmembrane domain of the MMTV glycoprotein is required 
      for proper transport and proteolytic processing, whereas, in the absence of the 
      transmembrane domain, the presence of a hydrophobic region of the ectodomain 
      correlated with retention at an early step in the exocytic pathway.
FAU - Platt, E J
AU  - Platt EJ
AD  - Department of Molecular and Cell Biology, University of California, Berkeley 
      94720.
FAU - Firestone, G L
AU  - Firestone GL
LA  - eng
GR  - CA-09041/CA/NCI NIH HHS/United States
GR  - DK-42799/DK/NIDDK NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
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 (Glycoproteins)
RN  - 0 (RNA, Viral)
SB  - IM
MH  - Blotting, Northern
MH  - Electrophoresis, Polyacrylamide Gel
MH  - *Exocytosis
MH  - Gene Expression
MH  - Glycoproteins/*genetics/metabolism
MH  - Hydrolysis
MH  - Mammary Tumor Virus, Mouse/*genetics
MH  - Mutation
MH  - Plasmids
MH  - Proviruses/metabolism
MH  - RNA, Viral/analysis
MH  - Transcription, Genetic
MH  - Transfection
MH  - Tumor Cells, Cultured
EDAT- 1991/10/15 00:00
MHDA- 1991/10/15 00:01
CRDT- 1991/10/15 00:00
PHST- 1991/10/15 00:00 [pubmed]
PHST- 1991/10/15 00:01 [medline]
PHST- 1991/10/15 00:00 [entrez]
AID - S0021-9258(18)55009-2 [pii]
PST - ppublish
SO  - J Biol Chem. 1991 Oct 15;266(29):19384-95.