@article{mbs:/content/journal/micro/10.1099/mic.0.26924-0, author = "Pardo, Mercedes and Monteoliva, Lucía and Vázquez, Paloma and Martínez, Raquel and Molero, Gloria and Nombela, César and Gil, Concha", title = "PST1 and ECM33 encode two yeast cell surface GPI proteins important for cell wall integrity", journal= "Microbiology", year = "2004", volume = "150", number = "12", pages = "4157-4170", doi = "https://doi.org/10.1099/mic.0.26924-0", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.26924-0", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", keywords = "CPY, carboxypeptidase Y", keywords = "CFW, Calcofluor White", keywords = "GPI, glycosyl phosphatidyl inositol", keywords = "PIR, protein with internal repeats", keywords = "Endo H, endoglycosaminidase H", abstract = "Pst1p was previously identified as a protein secreted by yeast regenerating protoplasts, which suggests a role in cell wall construction. ECM33 encodes a protein homologous to Pst1p, and both of them display typical features of GPI-anchored proteins and a characteristic receptor L-domain. Pst1p and Ecm33p are both localized to the cell surface, Pst1p being at the cell membrane and possibly also in the periplasmic space. Here, the characterization of pst1Δ, ecm33Δ and pst1Δ ecm33Δ mutants is described. Deletion of ECM33 leads to a weakened cell wall, and this defect is further aggravated by simultaneous deletion of PST1. As a result, the ecm33Δ mutant displays increased levels of activated Slt2p, the MAP kinase of the cell integrity pathway, and relies on a functional Slt2-mediated cell integrity pathway to ensure viability. Analyses of model glycosylated proteins show glycosylation defects in the ecm33Δ mutant. Ecm33p is also important for proper cell wall ultrastructure organization and, furthermore, for the correct assembly of the mannoprotein outer layer of the cell wall. Pst1p seems to act in the compensatory mechanism activated upon cell wall damage and, in these conditions, may partially substitute for Ecm33p.", }