Cell type specification
Three specific transcription factors are encoded at the MAT locus:
One general transcription factor, MADS type: MCM1
- exibits different activity in ha and halpha cells
- activator or repressor
PRE: pheromone response element
Mating type conversion:
- happens in haploid only
- during late G1 phase
- in one of mitotic products: mother cell
Asymmetric mitotic division: mother and daughter cells are different Example from other species: stem cells produce specialized siblings
Ash1 localized to daughter cells prevents Swi5 TF from activating expression of HO endonuclease -> restrict switching of mating types to mother cells
Why have asymmetric types: a & alpha?
Signal transduction pathway appears identical in a and α types.