THE LOCALIZATION OF CHITIN SYNTHASE IN MEMBRANOUS VESICLES (CHITOSOMES) IN NEUROSPORA-CRASSA

Polyclonal anti-chitin synthase antibodies raised against the Saccharo myces cerevisiae CHS2 gene product were used to identify and localize chitin synthase in the filamentous ascomycete Neurospora crassa. A sin gle band of approximately 110 kDa was observed in Western blots of tot al protein extracts of N. crassa, probed with these antibodies. Howeve r, several additional bands were labelled when membrane fraction prote ins (microsomes) were probed. Histo-immunochemical localization of chi tin synthase confirmed that the polypeptide is compartmentalized in me mbranous vesicles (chitosomes), which are abundant in the vicinity of the hyphal tip. TEM analysis did not reveal chitin synthase in the pla sma membrane. However, dense labelling of membrane-associated chitin s ynthase was observed by light-microscopic analysis of IV. crassa proto plasts and at young hyphal tips.