Differential Labeling of Cell-surface and Internalized Proteins after Antibody Feeding of Live Cultured Neurons

Abstract

In order to demonstrate the cell-surface localization of a putative transmembrane receptor in cultured neurons, we labeled the protein on the surface of live neurons with a specific primary antibody raised against an extracellular portion of the protein. Given that receptors are trafficked to and from the surface, if cells are permeabilized after fixation then both cell-surface and internal protein will be detected by the same labeled secondary antibody. Here, we adapted a method used to study protein trafficking ("antibody feeding") to differentially label protein that had been internalized by endocytosis during the antibody incubation step and protein that either remained on the cell surfa..