Abstract

The Endosomal Sorting Complex Required for Transport (ESCRT) complexes are components of an essential protein sorting machinery critical for receptor down-regulation, HIV budding and cytokinesis. Consequently, ESCRT machinery dysfunction contributes to many diseases ranging from cancer to neurodegeneration. Monoubiquitination (Ub) of plasma membrane receptors by Ub ligases in yeast and humans serves as a critical signal for receptor endocytosis and down-regulation. The speaker and his research group have identified five distinct protein complexes (ESCRT-0, -I, -II,–III and Vps4) that function in the recognition and sorting of ubiquitinated plasma membrane proteins. They have shown that the ordered assembly of the ESCRT apparatus on the surface of the endosome delineates a specific sorting domain which can sequester cargo, deform the membrane and complete the last steps of vesicle formation and fission required for the internalization (down-regulation) of membrane receptors into the endosomal lumen. Recently, the speaker and his research group also identified a new family of proteins, the ARTs for Arrestin-Related Trafficking adaptors, that function upstream of the ESCRTs at the plasma membrane during the selective recognition and ubiquitination of PM proteins. The speaker will discuss his recent work on the function and regulation of the ESCRT and ART protein complexes during the selective down-regulation of integral membrane proteins.

About the Speaker

Scott Emr is the Frank H.T. Rhodes Class of 1956 Professor of Molecular Biology and Genetics and Director of the Cornell Institute for Cell and Molecular Biology. He received his PhD degree in Molecular Genetics from Harvard Medical School in 1981. Prior to joining the faculty at Cornell, he has held positions at UC Berkeley, Caltech and UC San Diego School of Medicine (concurrently as an Investigator in the Howard Hughes Medical Institute; 1991-2007). Prof Emr counts among his early honors a Searle Scholars Award and an NSF Presidential Young Investigator Award. He has been elected a member of the US National Academy of Sciences (2007), the American Academy of Arts and Sciences (2004) and the American Academy of Microbiology (1998). In 2003, he was awarded the Hansen Foundation Gold Medal Prize for elucidating intracellular sorting and transport pathways. In 2007, he was awarded the Avanti Prize for his key contributions in understanding lipid signaling pathways.

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