CHARACTERIZATION OF THE COMPLETE PROTEIN DISULFIDE-ISOMERASE GENE OF SCHISTOSOMA-MANSONI AND IDENTIFICATION OF THE TISSUES OF ITS EXPRESSION

cDNA and genomic clones of Schistosoma mansoni containing the complete sequence of a homolog of protein disulfide isomerase have been identi fied. The protein disulfide isomerase gene in schistosomes is a single copy gene having a genomic structure that is very similar to that of man. The C-terminus of the deduced protein is KDEL which in mammals fu nctions as a signal sequence for retention of luminal proteins in the endoplasmic reticulum. Immunohistology and in situ hybridization ident ify the gastrodermis of the gut, the wall cells of the protonephridia, and the sustentacular cells of the testes to be the major tissues of protein disulfide isomerase gene expression. The protein disulfide iso merase of schistosomes, produced in an expression vector in Escherichi a coli, catalyzes disulfide/sulfhydryl isomerization in vitro.