In this episode Dr. Peter Walter from UCSF discusses his early work on the characterization of molecular pathways that regulate protein trafficking in the endoplasmic reticulum (ER), including discovery of the signal recognition particle and its receptor. He then talks about more recent work related to the unfolded protein response (UPR), including the discovery of IRE1, an ER kinase and RNAase that controls UPR gene expression. Enjoy.