GPI-anchored mannoproteins

The presence of peak 2, corresponding to elution of the mannoprotein responsible for tartrate stabilization, confirms that the bond is covalent. Some of the mannoproteins that share covalent bonds with glucane also have a special type of glycosylation, leading to a glycosyl-phosphatidyl-inositol (GPI). The use of a mutant strain (FBYII), deficient in GPI-anchored mannoproteins when cnltnred at 37°C (FBYII-37), showed that the mannoproteins responsible for tartrate stabilization had this type of glycosylation. Two types of mannoprotein extracts were obtained by enzyme hydrolysis of yeast cell walls (FBYII), cultmed at 24°C or 37°C. 

HPLC analysis of these two extracts (Figure 1.22) showed that peak 2 was absent when the cell walls came from yeast cultured at 37°C, i.e. deficient in GPI-anchored mannoproteins. These results ... 

The cell wall of S. cerevisiae is composed of glucan, mannoproteins, and chitin (Klis, 1994 Cid et al., 1995). Of the mannoproteins, some of them are first synthesized as GPI-anchored and mannosylated proteins. Subsequently, they are incorporated from the plasma membrane to the cell wall and are covalently linked to the glucan there. Therefore, some signals should exist for dictating the cell wall incorporation. One found at a short N-terminal region near the GPI-attached asparagine (the co-site) is important (Hamada et al., 1998b). Namely, a plasma membrane GPI-anchored protein was localized to the cell wall if the (V/I)... 

Fibrous Glucan Entrapped Mannoprotein Chitin GPI Anchor Plasma Membrane... 

In other work, Moine-Ledoux et al. (1997) reported that the use of Mannostab at doses ranging from 15g/hL to 25g/hL inhibit potassium bitartrate precipitation (Table 5.2) while excess amounts of this additive, that is 30g/hL, are ineffective on potassium bitartrate crystallization (Table 5.2). Within the extracts, compounds responsible for the stabilizing effect observed were found to be highly glycosylated mannoproteins of molecular masses ranging from 30 kDa to 40 kDa possessing a glycosyl-phosphadityl-inositol anchor (GPI) (Moine-Ledoux and Dubourdieu 1999, 2002,2007). 

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