Septum formation, cell division, and sporulation in mutants of yeast deficient in proteinase B.

Mutants of Saccharomyces cerevisiae that carry lesions in the structural gene for proteinase B, prb1, have been isolated. Proteinase B was thought to be involved in activation of chitin synthase zymogen to allow septum formation during budding and to be involved in sporulation. The prb1 mutants are able to grow and divide and they form apparently normal septa that contain chitin. Most diploids homozygous for prb1 mutations are unable to complete sporulation.