Cycling of the integral membrane glycoprotein, LEP100, between plasma membrane and lysosomes: kinetic and morphological analysis

Cell. 1987 Jun 5;49(5):669-77. doi: 10.1016/0092-8674(87)90543-5.


LEP100 (an integral membrane glycoprotein, Mr = 100,000) occurs in three subcellular compartments: lysosome (approximately 90% of the molecules), endosome (5%-8%), and plasma membrane (2%-3%). Rate constants for movement to and from each compartment have been estimated. The movement of LEP100 from endosomes to lysosomes was blocked by chloroquine, causing redistribution to a new steady state in which about 30% of LEP100 molecules were localized in clathrin-coated patches on the cell surface, while intracellular LEP100 occurred in nearby endocytic vesicles. The cell-surface and endosomal pools of LEP100 remained in rapid equilibrium (t1/2 about 5 min). These results support the existence of a hitherto unappreciated pathway of membrane flow from lysosomes. The lysosome should not be considered simply a terminal target of membrane trafficking.

Publication types

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

MeSH terms

  • Animals
  • Avian Proteins*
  • Cell Membrane / metabolism*
  • Chickens
  • Chloroquine / pharmacology
  • Clathrin / pharmacology
  • Coated Pits, Cell-Membrane / metabolism
  • Fibroblasts / metabolism
  • Kinetics
  • Lysosomes / metabolism*
  • Membrane Glycoproteins / metabolism*
  • Monensin / pharmacology


  • Avian Proteins
  • Clathrin
  • Membrane Glycoproteins
  • LEP100 protein, Gallus gallus
  • Chloroquine
  • Monensin