Ron Rieger Kopito (born 1954) is an American cell biologist and academic holding the position of Professor in the Department of Biology at Stanford University. He is most known for his work on proteostasis, particularly the role of ubiquitin and UFMylation in protein and ribosome quality control in the mammalian secretory pathway. Kopito is a Lifetime Fellow of the American Society for Cell Biology.
Kopito earned an A.B. in biochemistry from Bowdoin College in 1976. He then received his Ph.D. in nutritional biochemistry and metabolism from the Massachusetts Institute of Technology (MIT) in 1982.
Kopito was an NIH postdoctoral fellow and Lucille P. Markey Scholar at MIT and the Whitehead Institute from 1982 to 1986 under the mentorship of Harvey F. Lodish. In 1987, he joined the faculty of the Department of Biological Sciences (now the Department of Biology) at Stanford University, and became a full professor in 1996.
His research work has included genetics, cell physiological characterization of SLC4A anion transporters and the cystic fibrosis transmembrane conductance regulator, CFTR, defining the role of the ubiquitin proteasome system (UPS) in endoplasmic reticulum (ER) associated degradation (ERAD). He coined the term aggresome to describe intracellular inclusions that collect aggregated proteins and demonstrated that protein aggregates derived from the Huntington's disease gene product impair cellular proteostasis and can propagate between cells in a prion-like manner. He discovered that UFMylation of the large ribosomal subunit is required for ribosome-associated quality control and translocon recycling at the ER, resolving a 50-year-old cell biological mystery.