FIG 5.

Lack of N-linked hypermannose (mannan) outer chains in Pneumocystis. Like C. albicans, Pneumocystis spp. are able to synthesize the N-linked glycan core structure (containing up to nine mannose residues, as indicated on the left) in the cytoplasm and the endoplasmic reticulum (ER). However, due to the loss of multiple enzymes, Pneumocystis spp. are unable to synthesize the α-1,6-linked mannose backbone as well as the α-1,2- and α-1,3-linked mannose outer chains seen in C. albicans (square brackets), which are synthesized in the Golgi apparatus. (Diagrams of the N-linked mannan structure in C. albicans and Pneumocystis were adapted from reference 69.)