Mating type proteins are sequence specific DNA-binding proteins that act as master switches in yeast differentiation by controlling gene expression in a cell type-specific fashion. Transcriptional corepressor that acts in conjunction with ALPHA2 to repress transcription both of homozygote-specific genes and of genes necessary for the white-opaque switch, a prerequisite for mating. Forms a heterodimer with ALPHA2. Moderately repressed by HBR1 in response to hemoglobin and growth signals. The C.albicans mating-type-like (MTL) locus contains, in addition to the genes for the regulatory proteins (MTLA1, MTLA2, MTLALPHA1 and MTLALPHA2), a and alpha idiomorphs of a phosphatidylinositol kinase (PIKA and PIKALPHA), a poly(A) polymerase (PAPA and PAPALPHA) and an oxysterol binding protein-like protein (OBPA and OBPALPHA). Most C.albicans strains are heterozygous at the MTL locus and do not readily undergo white-opaque switching and mating, but mating occurs in hemi- or homozygous strains. Mating takes place in opaque cells, produces tetraploid progeny and seems to occur rarely, if at all, in nature. Conservation of mating capacity is rather thought to be due to the simultaneously regulated white-opaque switch, which seems to play an important role in host commensalism. Belongs to the MATA1 family.