Determinants for glycophospholipid anchoring of the Saccharomyces cerevisiae GAS1 protein to the plasma membrane.
A 125-kDa glycoprotein exposed on the surface of Saccharomyces cerevisiae cells belongs to a class of eucaryotic membrane proteins anchored to the lipid bilayer by covalent linkage to an inositol-containing glycophospholipid. We have cloned the gene (GAS1) encoding the 125-kDa protein (Gas1p) and found that the function of Gas1p is not essential for cell viability. The nucleotide sequence of GAS1 predicts a 60-kDa polypeptide with a cleavable N-terminal signal sequence, potential sites for N- and O-linked glycosylation, and a C-terminal hydrophobic domain. Determination of the anchor attachment site revealed that the C-terminal hydrophobic domain of Gas1p is removed during anchor addition. However, this domain is essential for addition of the glycophospholipid anchor, since a truncated form of the protein failed to become attached to the membrane. Anchor addition was also abolished by a point mutation affecting the hydrophobic character of the C-terminal sequence. We conclude that glycophospholipid anchoring of Gas1p depends on the integrity of the C-terminal hydrophobic domain that is removed during anchor attachment.
Nuoffer
C
C
Biocenter, University of Basel, Switzerland.
Jenö
P
P
Conzelmann
A
A
Riezman
H
H
D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D006017:Glycolipids / Q000378:metabolism*; D017261:Glycosylphosphatidylinositols; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008969:Molecular Sequence Data; D009841:Oligonucleotides; D010716:Phosphatidylinositols / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D013329:Structure-Activity Relationship
D005656:Fungal Proteins; C066709:GAS1 protein, S cerevisiae; D006017:Glycolipids; D017261:Glycosylphosphatidylinositols; D008562:Membrane Glycoproteins; D009841:Oligonucleotides; D010716:Phosphatidylinositols; D029701:Saccharomyces cerevisiae Proteins