AG alpha 1 is the structural gene for the Saccharomyces cerevisiae alpha-agglutinin, a cell surface glycoprotein involved in cell-cell interactions during mating.

AUTOR(ES)

Lipke, P N

RESUMO

We have cloned the alpha-agglutinin structural gene, AG alpha 1, by the isolation of alpha-specific agglutination-defective mutants, followed by isolation of a complementing plasmid. Independently isolated alpha-specific agglutination-defective mutations were in a single complementation group, consistent with biochemical results indicating that the alpha-agglutinin is composed of a single polypeptide. Mapping results suggested that the complementation group identified by these mutants is allelic to the ag alpha 1 mutation identified previously. Expression of AG alpha 1 RNA was alpha specific and inducible by a-factor. Sequences similar to the consensus sequences for positive control by MAT alpha 1 and pheromone induction were found upstream of the AG alpha 1 initiation codon. The AG alpha 1 gene could encode a 650-amino-acid protein with a putative signal sequence, 12 possible N-glycosylation sites, and a high proportion of serine and threonine residues, all of which are features expected for the alpha-agglutinin sequence. Disruption of the AG alpha 1 gene resulted in failure to express alpha-agglutinin and loss of cellular agglutinability in alpha cells. An Escherichia coli fusion protein containing 229 amino acids of the AG alpha 1 sequence was recognized by an anti-alpha-agglutinin antibody. In addition, the ability of this antibody to inhibit agglutination was prevented by this fusion protein. These results indicate that AG alpha 1 encodes alpha-agglutinin. Features of the AG alpha 1 gene product suggest that the amino-terminal half of the protein contains the a-agglutinin binding domain and that the carboxy-terminal half contains a cell surface localization domain, possibly including a glycosyl phosphatidylinositol anchor.

Documentos Relacionados

• Courtship in Saccharomyces cerevisiae: an early cell-cell interaction during mating.
• Identification of glycoprotein components of alpha-agglutinin, a cell adhesion protein from Saccharomyces cerevisiae.
• Mating type-specific cell-cell recognition of Saccharomyces cerevisiae: cell wall attachment and active sites of a- and alpha-agglutinin.
• Cell-cell recognition in yeast: isolation of intact alpha-agglutinin from Saccharomyces kluyveri.
• Cell surface anchorage and ligand-binding domains of the Saccharomyces cerevisiae cell adhesion protein alpha-agglutinin, a member of the immunoglobulin superfamily.