ABSTRACT
This chapter deals with the pathways leading to the synthesis of the primary polysaccharides of yeast cell envelopes, namely glucan, chitin, and mannan. It also deals with the localization of the glycosyltransferases and some of the mechanisms by which the formations of the polymers are thought to be regulated. Presently there are only hints about the ways in which syntheses of chitin and glucan are regulated. Concerning glucan, it is not known if the branching points are constituted by transferases acting on nucleoside diphosphate glucose donors or whether a branching enzyme breaks an existing linkage and forms a new linkage. Mannan is a generic name for different polysaccharides having in common a high proportion of mannose residues. Unlike chitin or glucan, mannans are readily soluble in water once extracted from the cells and do not appear to contribute to the shape of the organisms.
