Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States; Howard Hughes Medical Institute, California Institute of Technology, Pasadena, United states
Yang Li
Cardiometabolic Disorders, Amgen Inc. Discovery Research, South San Francisco, United states; Surrozen Inc, South San Francisco, United states
Roger D Kornberg
Department of Structural Biology, Stanford University School of Medicine, Stanford, United States
The fibroblast growth factor FGF21 was labeled with molecularly defined gold nanoparticles (AuNPs), applied to human adipocytes, and imaged by cryo-electron tomography (cryo-ET). Most AuNPs were in pairs about 80 Å apart, on the outer cell surface. Pairs of AuNPs were also abundant inside the cells in clathrin-coated vesicles and endosomes. AuNPs were present but no longer paired in multivesicular bodies. FGF21 could thus be tracked along the endocytotic pathway. The methods developed here to visualize signaling coupled to endocytosis can be applied to a wide variety of cargo and may be extended to studies of other intracellular transactions.
