457 Weill Hall
Chris Fromme is an Assistant Professor in the Weill Institute for Cell and Molecular Biology and the Department of Molecular Biology and Genetics. After graduating from Cornell with a B.A. in Biology in 1999, Chris did his graduate studies at Harvard University, receiving a Ph.D. in Biochemistry in 2004. He then did postdoctoral work as a Miller Institute Fellow at UC Berkeley, where he began his work on protein trafficking and membrane transport. He joined the Cornell faculty in 2008.
Our lab is interested in how proteins and membranes are trafficked within eukaryotic cells. Regulated transport of proteins between distinct membrane bound compartments is crucial for maintaining the homeostatic balance of the endomembrane system. The Golgi complex is the primary sorting organelle in eukaryotic cells, and virtually all traffic out of the Golgi is controlled by GTPases of the Arf family. Arf GTPases are activated to their GTP-bound form at the Golgi by Arf-GEF (Guanine nucleotide Exchange Factor) proteins of the BIG/GBF family. Activated (GTP-bound) Arf GTPases recruit effectors that form vesicles and sort cargos. Although the basic mechanism of Arf activation – nucleotide exchange by the GEF domain – is well characterized, there are two important unresolved questions regarding the Golgi-localized Arf-GEFs: How is their GEF activity regulated? How do they achieve their specific localization? We study these and other mechanistic questions regarding Arf GTPase regulation using biochemical, structural, and cell biological approaches.
We are also investigating the structure and function of the "exomer" vesicle coat. Exomer is an Arf1-dependent protein complex responsible for the transport of select proteins in the late secretory pathway of most single-celled eukaryotes. Exomer is not related to any other known coat protein complexes, and therefore represents an exciting opportunity for study. Exomer-based transport is polarized, directing proteins to specific sub-domains of the plasma membrane. Some proteins transported by exomer are also localized in a cell-cycle dependent manner. We seek to understand how exomer cargo sorting is regulated spatiotemporally. We are using structural, biochemical, and cell biological tools to investigate exomer function.
*Paczkowski, J.E., *Richardson, B.C., Strassner, A.M., and Fromme, J.C. "The exomer cargo adaptor structure reveals a novel GTPase-binding domain." EMBO J. 31 (2012) 4191-4203.
Richardson, B.C., and Fromme, J.C., "Autoregulation of Sec7 Arf-GEF activity and localization by positive feedback." Small GTPases.3(2012) [Sep. 20 Epub]
Richardson, B.C., McDonold, C.M., and Fromme, J.C. "The Sec7 Arf-GEF is recruited to the trans-Golgi network by positive feedback." Developmental Cell 22 (2012) 799-810.
Fromme, J.C. and Kim, J. "A rapid and quantitative coat protein complex II vesicle formation assay using luciferase reporters." Anal. Biochem. 421 (2012) 482-488.