Selection of axial growth sites in yeast requires Axl2p, a novel plasma membrane glycoprotein.
Spa2p and Cdc10p both participate in bud site selection and cell morphogenesis in yeast, and spa2delta cdc10-10 cells are inviable. To identify additional components important for these processes in yeast, a colony-sectoring assay was used to isolate high-copy suppressors of the spa2delda cdc10-10 lethality. One such gene, AXL2, has been ... characterized in detail. axl2 cells are defective in bud site selection in haploid cells and bud in a bipolar fashion. Genetic analysis indicates that AXL2 falls into the same epistasis group as BUD3. Axl2p is predicted to be a type I transmembrane protein. Tunicamycin treatment experiments, biochemical fractionation and extraction experiments, and proteinase K protection experiments collectively indicate that Axl2p is an integral membrane glycoprotein at the plasma membrane. Indirect immunofluorescence experiments using either Axl2p tagged with three copies of a hemagglutinin epitope or high-copy AXL2 and anti-Axl2p antibodies reveal a unique localization pattern for Axl2p. The protein is present as a patch at the incipient bud site and in emerging buds, and at the bud periphery in small-budded cells. In cells containing medium-sized or large buds, Axl2p is located as a ring at the neck. Thus, Axl2p is a novel membrane protein critical for selecting proper growth sites in yeast. We suggest that Axl2p acts as an anchor in the plasma membrane that helps direct new growth components and/or polarity establishment components to the cortical axial budding site.
Mesh Terms:
Amino Acid Sequence, Base Sequence, Cell Compartmentation, Cell Division, Cell Fractionation, Cell Membrane, Cell Polarity, Cloning, Molecular, Fungal Proteins, GTPase-Activating Proteins, Gene Deletion, Genes, Fungal, Genes, Suppressor, Haploidy, Intracellular Signaling Peptides and Proteins, Lipoproteins, Membrane Glycoproteins, Models, Biological, Molecular Sequence Data, Mutagenesis, Peptides, Pheromones, Protein Conformation, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Sequence Analysis, DNA
Amino Acid Sequence, Base Sequence, Cell Compartmentation, Cell Division, Cell Fractionation, Cell Membrane, Cell Polarity, Cloning, Molecular, Fungal Proteins, GTPase-Activating Proteins, Gene Deletion, Genes, Fungal, Genes, Suppressor, Haploidy, Intracellular Signaling Peptides and Proteins, Lipoproteins, Membrane Glycoproteins, Models, Biological, Molecular Sequence Data, Mutagenesis, Peptides, Pheromones, Protein Conformation, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Sequence Analysis, DNA
Genes Dev.
Date: Apr. 01, 1996
PubMed ID: 8846915
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