The Gas1 glycoprotein, a putative wall polymer cross-linker.
The yeast cell wall, which for years has been regarded as a static cellular component, has been revealed to be dynamic in its structure and composition and complex in its enzymatic activity. The S. cerevisiae cell wall is composed of beta-1,3/beta-1,6-glucans, mannoproteins, and chitin, which are assembled into an extracellular matrix essential for maintenance of cell integrity. Gas1p, a glycoprotein anchored to the outer leaflet of the plasma membrane through a glycosylphosphatidylinositol, plays a key role in cell wall assembly. Loss of Gas1p leads to several morphogenetic defects and to a decrease in the amount of cross-links between the cell wall glucans. These defects in turn trigger a compensatory response that guarantees cell viability. Several Gas1p homologs have been isolated from Candida species and S. pombe. The Gas1p family also includes two plant proteins with endo-beta-1,3-glucanase activity. Sequence comparisons reveal that Gas1p family proteins have a modular organization of domains. The genetic and molecular analyses reviewed here suggest that Gas1p could play a role as a polymer cross-linker, presumably by catalyzing a transglycosylation reaction.
Popolo
L
L
Università degli Studi di Milano, Dipartimento di Fisiologia e Biochimica Generali, Via Celoria 26, 20133 Milan, Italy.
Vai
M
M
D000595:Amino Acid Sequence; D002470:Cell Survival; D002473:Cell Wall / Q000737:chemistry / Q000378:metabolism*; D002686:Chitin / Q000378:metabolism; D005786:Gene Expression Regulation; D017261:Glycosylphosphatidylinositols / Q000737:chemistry; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D011108:Polymers / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment
C066709:GAS1 protein, S cerevisiae; D017261:Glycosylphosphatidylinositols; D008562:Membrane Glycoproteins; D011108:Polymers; D029701:Saccharomyces cerevisiae Proteins; D002686:Chitin