Cell-free transport from the trans-golgi network to late endosome requires factors involved in formation and consumption of clathrin-coated vesicles

J Biol Chem. 2005 Feb 11;280(6):4442-50. doi: 10.1074/jbc.M412553200. Epub 2004 Nov 30.

Abstract

Transport between the trans-Golgi network (TGN) and late endosome represents a conserved, clathrin-dependent sorting event that separates lysosomal from secretory cargo molecules and is also required for localization of integral membrane proteins to the TGN. Previously, we reported a cell-free reaction that reconstitutes transport from the yeast TGN to the late endosome/prevacuolar compartment (PVC) and requires the PVC t-SNARE Pep12p. Here, we report that factors required both for formation of clathrin-coated vesicles at the TGN (the Chc1p clathrin heavy chain and the Vps1p dynamin homolog) and for vesicle fusion at the PVC (the Vps21p rab protein and Vps45p SM (Sec1/Munc18) protein) are required for cell-free transport. The marker for TGN-PVC transport, Kex2p, is initially present in a clathrin-containing membrane compartment that is competent for delivery of Kex2p to the PVC. A Kex2p chimera containing the cytosolic tail (C-tail) of the vacuolar protein sorting receptor, Vps10p, is also efficiently transported to the PVC. Antibodies against the Kex2p and Vps10p C-tails selectively block transport of Kex2p and the Kex2-Vps10p chimera. The requirements for factors involved in vesicle formation and fusion, the identification of the donor compartment as a clathrin-containing membrane, and the need for accessibility of C-tail sequences argue that the TGN-PVC transport reaction involves selective incorporation of TGN cargo molecules into clathrin-coated vesicle intermediates. Further biochemical dissection of this reaction should help elucidate the molecular requirements and hierarchy of events in TGN-to-PVC sorting and transport.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alleles
  • Biological Transport
  • Cell Membrane / metabolism
  • Cell-Free System
  • Clathrin / chemistry
  • Clathrin / metabolism*
  • Cytosol / metabolism
  • Endosomes / metabolism
  • Fungal Proteins / metabolism
  • Lysosomes / metabolism
  • Membrane Proteins / metabolism
  • Models, Biological
  • Mutation
  • Plasmids / metabolism
  • Proprotein Convertases / metabolism
  • Protein Structure, Tertiary
  • Qa-SNARE Proteins
  • Recombinant Fusion Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / metabolism
  • Subcellular Fractions
  • Vesicular Transport Proteins / metabolism
  • rab GTP-Binding Proteins / metabolism
  • trans-Golgi Network / metabolism*

Substances

  • Clathrin
  • Fungal Proteins
  • Membrane Proteins
  • PEP12 protein, S cerevisiae
  • Qa-SNARE Proteins
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae Proteins
  • VPS45 protein, S cerevisiae
  • Vesicular Transport Proteins
  • Proprotein Convertases
  • KEX2 protein, S cerevisiae
  • VPS21 protein, S cerevisiae
  • rab GTP-Binding Proteins