Identification and characterization of extragenic suppressors of the yeast sec12 ts mutation

The product of the yeast SEC12 gene is the most upstream player as far as we know in the events of vesicle budding from the endoplasmic reticulum membrane. To understand how the Sec12p function could be regulated, I identified three extragenic suppressor mutations of the sec12 ts mutation. RST1DS is a dominant mutation and causes elevated expression of Sec12p. rst2 and rst3 are recessive and give pleiotropic phenotypes including slow growth at low temperatures and heterogeneous modification of Sec12p. Their possible roles are discussed.