Figure 1.

The organization of the A43 mating type locus of C. cinereus. Arrows designate direction of transcription; the a2 gene is transcribed but nonfunctional (gray arrow). Boxes denote the location of predicted homeodomain-like (HD) motifs. The members of a gene pair, e.g., the b1 and the b2 genes, are characterized by the presence of two types of HD motifs, HD1 and HD2. The hypervariable 5′ regions are shown as shaded boxes. The open boxes indicate two regions of recombination. (Adapted from refs. 13 and 20.)