The mating type genes in A loci encode two kinds of highly conserved homeodomain containing protein, which play important roles in A dependent development by the formation of protein heterodimer.

• A位点的交配型基因编码两类含相似同源结构域的蛋白质，两种蛋白质形成异源二聚体，调节依赖A因子的发育过程；