Whi7/Srl3 polymorphisms reveal its role in cell size and quiescence.

Whi5 and Srl3/Whi7 are related proteins that resulted from the whole genome duplication of (Wolfe and Shields 1997). Whi5 plays an Rb-like function in binding and inhibiting the late G1 transcription that promotes progression from G1 to S (Costanzo 2004; de Bruin 2004). Whi7 can also associate with G1 transcription complexes and promotes G1 arrest when overproduced (Gomar-Alba 2017), but its transcription is primarily induced by stress (Ragni 2011; Mendez 2020). We have used polymorphisms in two laboratory yeast strains to uncover novel functions of Whi7 in log and quiescent cells. These include small cell size during log phase and defects in entry, maintenance and recovery from quiescence.