Transcription factor required for successful completion of meiosis and spore formation. Gets activated after completion of meiotic recombination at the end of prophase I. Recognizes and binds to the middle sporulation element (MSE) 5'-C[AG]CAAA[AT]-3' in the promoter region of stage-specific genes that are required for progression through meiosis and sporulation. Competes for binding to MSE with the transcriptional repressor SUM1, which represses middle sporulation-specific genes during mitosis and early sporulation. Binds to DNA as a monomer. Induced during prophase I of meiosis. Requires protein kinase IME2 for initial expression and continued transcription during meiotic divisions. Can autoactivate its own synthesis. Phosphorylated by pachytene checkpoint kinase IME2, but also phosphorylated in an IME2-independent manner. Phosphorylation probably eliminates SUM1-mediated repression and is also required for full transcriptional activation activity. Phosphorylation of the DNA-binding domain by IME2 does not alter DNA binding affinity.