Endocytic pathways and endosomal trafficking: a primer

Wien Med Wochenschr. 2016 May;166(7-8):196-204. doi: 10.1007/s10354-016-0432-7. Epub 2016 Feb 9.


This brief overview of endocytic trafficking is written in honor of Renate Fuchs, who retires this year. In the mid-1980s, Renate pioneered studies on the ion-conducting properties of the recently discovered early and late endosomes and the mechanisms governing endosomal acidification. As described in this review, after uptake through one of many mechanistically distinct endocytic pathways, internalized proteins merge into a common early/sorting endosome. From there they again diverge along distinct sorting pathways, back to the cell surface, on to the trans-Golgi network or across polarized cells. Other transmembrane receptors are packaged into intraluminal vesicles of late endosomes/multivesicular bodies that eventually fuse with and deliver their content to lysosomes for degradation. Endosomal acidification, in part, determines sorting along this pathway. We describe other sorting machinery and mechanisms, as well as the rab proteins and phosphatidylinositol lipids that serve to dynamically define membrane compartments along the endocytic pathway.

Keywords: Caveolae-mediated endocytosis; Clathrin-dependent endocytosis; Clathrin-independent endocytosis; Clathrin-mediated endocytosis; Endocytic trafficking; Endocytosis; Endosomes; Multivesicular bodies; Phosphatidylinositol phospholipids; Rab proteins; Rabs.

Publication types

  • Review

MeSH terms

  • Acid-Base Equilibrium / physiology*
  • Animals
  • Clathrin / physiology
  • Endocytosis / physiology*
  • Endosomal Sorting Complexes Required for Transport / physiology*
  • Humans
  • Multivesicular Bodies / physiology*


  • Clathrin
  • Endosomal Sorting Complexes Required for Transport