Secreted agglutinability-masking factors in Issatchenkia scutulata var. scutulata.

The agglutinability-masking factors (AMFs) of a and alpha mating types of Issatchenkia scutulata var. scutulata were prepared from culture fluids. AMFs masked the agglutinability of opposite mating-type cells sex-specifically, just like agglutination substances responsible for sexual cell agglutination. a AMF adsorbed to alpha cells was eluted by incubating the cells at 60 degrees C for 10 min. alpha AMF was prepared directly from culture fluids of alpha cells by DEAE-cellulose ion exchange chromatography. The active part of the AMFs is thought to be a peptidyl moiety because of the sensitivity to subtilisin. The pretreatment of cells with AMF of the opposite mating-type was shown to promote zygote formation. alpha AMF slightly inhibited growth in a cells but not in alpha cells, while a AMF did not show any growth-inhibitory effect on either a or x cells.