A GENE RESPONSIBLE FOR VEGETATIVE INCOMPATIBILITY IN THE FUNGUS PODOSPORA-ANSERINA ENCODES A PROTEIN WITH A GTP-BINDING MOTIF AND G-BETA HOMOLOGOUS DOMAIN

The het-e-1 gene of the fungus Podospora anserina is responsible for v egetative incompatibility through specific interactions with different alleles of the unlinked gene, het-c. Coexpression of two incompatible genes triggers a cell death reaction that prevents heterokaryon forma tion. The het-e1 allele has been cloned to get information on the func tion of the locus. It encodes a putative 1356-amino-acid polypeptide t hat displays two sequence motifs that have not yet been reported to be present on a single polypeptide. They are a GTP-binding domain and a repeated region that shares similarity with that of the beta-transduci n. Contrary to other members of the beta-transducin family, sequence c onservation between the repeated units is very strong and the number o f repeats is different in wild-type het-e alleles.