Screening for mutants defective in secretory protein maturation and ER quality control

A genetic strategy devised to understand the physiology of the unfolded protein response serendipitously generated mutants affecting a broad spectrum of functions needed for secretory protein biogenesis and quality control. These included N- and O-linked glycosylation, glycosylphosphatidylinositol anchor biosynthesis and transfer, protein folding, protein trafficking, lumenal ionic homeostasis, ER quality control, and ER associated protein degradation. As these pathways are incompletely understood, the screen provides a simple method for their genetic dissection. This article describes methods for isolating novel mutants of these pathways and strategies for identifying corresponding genes.