Membrane insertion of uracil permease, a polytopic yeast plasma membrane protein.
Uracil permease is a multispanning protein of the Saccharomyces cerevisiae plasma membrane which is encoded by the FUR4 gene and produced in limited amounts. It has a long N-terminal hydrophilic segment, which is followed by 10 to 12 putative transmembrane segments, and a hydrophilic C terminus. The protein carries seven potential N-linked glycosylation sites, three of which are in its N-terminal segment. Overexpression of this permease and specific antibodies were used to show that uracil permease undergoes neither N-linked glycosylation nor proteolytic processing. Uracil permease N-terminal segments of increasing lengths were fused to a reporter glycoprotein, acid phosphatase. The in vitro and in vivo fates of the resulting hybrid proteins were analyzed to identify the first signal anchor sequence of the permease and demonstrate the cytosolic orientation of its N-terminal hydrophilic sequence. In vivo insertion of the hybrid protein bearing the first signal anchor sequence of uracil permease into the endoplasmic reticulum membrane was severely blocked in sec61 and sec62 translocation mutants.
Silve
S
S
Institut Jacques Monod, Université Paris VII, France.
Volland
C
C
Garnier
C
C
Jund
R
R
Chevallier
M R
MR
Haguenauer-Tsapis
R
R
D015153:Blotting, Western; D002462:Cell Membrane / Q000201:enzymology; D003001:Cloning, Molecular; D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000235:genetics; D005800:Genes, Fungal; D006031:Glycosylation; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000235:genetics; D026901:Membrane Transport Proteins / Q000096:biosynthesis / Q000235:genetics*; D008961:Models, Structural; D033704:Nucleotide Transport Proteins; D010957:Plasmids; D014176:Protein Biosynthesis; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D014158:Transcription, Genetic
D004251:DNA Transposable Elements; C035528:FUR4 protein, S cerevisiae; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D033704:Nucleotide Transport Proteins; D029701:Saccharomyces cerevisiae Proteins