Role of cyclin G-associated kinase in uncoating clathrin-coated vesicles from non-neuronal cells

J Biol Chem. 2000 Jan 14;275(2):1365-70. doi: 10.1074/jbc.275.2.1365.


Auxilin is a brain-specific DnaJ homolog that is required for Hsc70 to dissociate clathrin from bovine brain clathrin-coated vesicles. However, Hsc70 is also involved in uncoating clathrin-coated vesicles formed at the plasma membrane of non-neuronal cells suggesting that an auxilin homolog may be required for uncoating in these cells. One candidate is cyclin G-associated kinase (GAK), a 150-kDa protein expressed ubiquitously in various tissues. GAK has a C-terminal domain with high sequence similarity to auxilin; like auxilin this C-terminal domain consists of three subdomains, an N-terminal tensin-like domain, a clathrin-binding domain, and a C-terminal J-domain. Western blot analysis shows that GAK is present in rat liver, bovine testes, and bovine brain clathrin-coated vesicles. More importantly, liver clathrin-coated vesicles, which contain GAK but not auxilin, are uncoated by Hsc70, suggesting that GAK acts as an auxilin homolog in non-neuronal cells. In support of this view, the clathrin-binding domain of GAK alone induces clathrin polymerization into baskets and the combined clathrin-binding domain and J-domain of GAK supports uncoating of AP180-clathrin baskets by Hsc70 at pH 7 and induces Hsc70 binding to clathrin baskets at pH 6. Immunolocalization studies suggest that GAK is a cytosolic protein that is concentrated in the perinuclear region; it appears to be highly associated with the trans-Golgi where the budding of clathrin-coated vesicles occurs. We propose that GAK is a required cofactor for the uncoating of clathrin-coated vesicles by Hsc70 in non-neuronal cells.

MeSH terms

  • Adaptor Proteins, Vesicular Transport
  • Animals
  • Binding Sites
  • Brain / enzymology
  • Cattle
  • Clathrin / metabolism*
  • Clathrin / ultrastructure
  • Coated Pits, Cell-Membrane / metabolism*
  • Cyclins / metabolism*
  • Golgi Apparatus / metabolism
  • Golgi Apparatus / ultrastructure
  • HeLa Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins
  • Kinetics
  • Liver / enzymology
  • Male
  • Monomeric Clathrin Assembly Proteins*
  • Nerve Tissue Proteins / metabolism
  • Phosphoproteins / metabolism
  • Protein-Serine-Threonine Kinases / metabolism*
  • Rats
  • Recombinant Proteins / metabolism
  • Testis / enzymology
  • Transfection


  • Adaptor Proteins, Vesicular Transport
  • Clathrin
  • Cyclins
  • Gak protein, rat
  • Intracellular Signaling Peptides and Proteins
  • Monomeric Clathrin Assembly Proteins
  • Nerve Tissue Proteins
  • Phosphoproteins
  • Recombinant Proteins
  • clathrin assembly protein AP180
  • GAK protein, human
  • Protein-Serine-Threonine Kinases