MATA1_YEASX MAT1A 126 MATA1 Mating-type protein A1 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, in a/alpha diploid cells, binds cooperatively with the ALPHA2 protein to a 21-bp DNA sequence termed the haploid-specific gene (hsg) operator, to repress transcription of haploid-specific genes and of MATALPHA1. MDDICSMAENINRTLFNILGTEIDEINLNTNNLYNFIMESNLTKVEQHTLHKNISNNRLEIYHHIKKEKSPKGKSSISPQARAFLEQVFRRKQSLNSKEKEEVAKKCGITPLQVRVWFINKRMRSK