The A alpha 6 locus: its relation to mating-type regulation of sexual development in Schizophyllum commune

We have isolated and examined the A alpha6 mating-type locus of Schizophyll um commune as a first step toward resolving a functional difference between this locus and the Aa loci previously studied. Our analyses show Aa6 to be remarkably similar to the Ao loci of known structure. The locus is compose d of two, divergently transcribed genes similar in size to known Z and Y ge nes of the AY loci. We have. termed the two genes, Z6 and Y6. on the basis of their demonstrated mating activities and encoded protein motifs. The Z6 gene encodes a homeodomain-related sequence, two acidic regions and a predi cted coiled-coil motif. The Y6 gene encodes a homeodomain, predicted coiled -coil motif, two regions with homology to the A beta locus gene V6, a basic region encoding a putative nuclear localization sequence and a serine-rich region. The Z6 and Y6 proteins share these features with the other known Z and Y proteins, respectively. One of the two amino acid sequences with hom ology to the A beta V6 protein has not previously been reported.