The Kopito laboratory seeks a molecular understanding of how cells maintain the fidelity of their proteomes. Unlike DNA, which can be repaired if damaged or incorrectly made, proteins cannot be mended. Instead, damaged or incorrectly synthesized proteins must be rapidly and efficiently destroyed lest they form toxic aggregates. Our laboratory use state-of-the-art cell biological, genetic and systems-level approaches to understand how proteins are correctly synthesized, folded and assembled in the mammalian secretory pathway, how errors in this process are detected and how abnormal proteins are destroyed by the ubiquitin-proteasome system.