Schizosaccharomyces pombe cell walls contain two major glycoprotein species, I and II, with molecular masses of 2 x 10(6) and 5 x 10(5) Da respectively, as determined by gel filtration chromatography and PAGE. The ratio of sugar to protein is higher in species I than in species II. Much of the sugar in both glycoproteins (about 85% in wild-type cells) is O-linked to the peptide moiety. The morphological sph1 mutant is resistant to papulacandin B, and its cell wall contains less glycoprotein II (but not less glycoprotein I) than the parental wild-type strain, although glycoprotein II is still synthesized and released into the growth medium. Papulacandin B largely reverses the morphological alteration of the mutant, and returns the ratio between species I and II to about that found in the parental strain, although the absolute amount of species II is still lower in the mutant. The results point to the importance of the relative amounts of the different wall polymers in determining cell morphology.