Clathrin terminal domain-ligand interactions regulate sorting of mannose 6-phosphate receptors mediated by AP-1 and GGA adaptors [Membrane Biology]

January 9th, 2014 by Stahlschmidt, W., Robertson, M. J., Robinson, P. J., McCluskey, A., Haucke, V.

Clathrin plays important roles in intracellular membrane traffic including endocytosis of plasma membrane proteins and receptors and protein sorting between the trans-Golgi network (TGN) and endosomes. Whether clathrin serves additional roles in receptor recycling, degradative sorting, or constitutive secretion has remained somewhat controversial. Here we have used acute pharmacological perturbation of clathrin terminal domain (TD) function to dissect the role of clathrin in intracellular membrane traffic. We report that internalization of major histocompatibility complex I (MHCI) is inhibited in cells depleted of clathrin or its major adaptor AP-2, a phenotype mimicked by application of Pitstop inhibitors of clathrin TD function. Hence, MHCI endocytosis occurs via a clathrin/ AP-2-dependent pathway. Acute perturbation of clathrin also impairs the dynamics of intracellular clathrin/ AP-1 or GGA-coated structures at the TGN/ endosomal interface, resulting in the peripheral dispersion of mannose 6-phosphate receptors (MPRs). By contrast, secretory traffic of vesicular stomatitis virus G protein (VSVG), recycling of internalized transferrin from endosomes, or degradation of epidermal growth factor receptor (EGFR) proceed unperturbed in cells with impaired clathrin TD function. These data indicate that clathrin is required for the function of AP-1- and GGA-coated carriers at the TGN but may be dispensable for outward traffic en route to the plasma membrane.
  • Posted in Journal of Biological Chemistry, Publications
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