Chapter 6 Rapid Endosomal Recycling

Peripheral membrane proteins are endocytosed by constitutive processes of membrane invaginations, followed by internalization driven by diverse endocytic machinery available at the cell surface. It is believed that after endocytic uptake, cargo proteins proceed either through the endosomal recycling circuit of the cell or travel toward late endosomes for degradation. In this chapter, we analyzed trafficking of seven cargo molecules (transferrin receptor, fully conformed MHC-I, non-conformed MHC-I, cholera-toxin B subunit, CD44, ICAM1, and G-protein-coupled receptor Rae-1) known to use the distinct endocytic route. For that purpose, we developed the software for multicompartment analysis of intracellular trafficking. We demonstrate that all endocytosed molecules are rapidly recycled and propose that the rapid recycling is a constitutive process that should be considered in the analysis of intracellular trafficking of peripheral membrane proteins.