Clathrin regulates the association of PIPKIgamma661 with the AP-2 adaptor beta2 appendage

J Biol Chem. 2009 May 15;284(20):13924-13939. doi: 10.1074/jbc.M901017200. Epub 2009 Mar 14.


The AP-2 clathrin adaptor differs fundamentally from the related AP-1, AP-3, and AP-4 sorting complexes because membrane deposition does not depend directly on an Arf family GTPase. Instead phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P(2)) appears to act as the principal compartmental cue for AP-2 placement at the plasma membrane as well as for the docking of numerous other important clathrin coat components at the nascent bud site. This PtdIns(4,5)P(2) dependence makes type I phosphatidylinositol 4-phosphate 5-kinases (PIPKIs) lynchpin enzymes in the assembly of clathrin-coated structures at the cell surface. PIPKIgamma is the chief 5-kinase at nerve terminals, and here we show that the 26-amino acid, alternatively spliced C terminus of PIPKIgamma661 is an intrinsically unstructured polypeptide that binds directly to the sandwich subdomain of the AP-2 beta2 subunit appendage. An aromatic side chain-based, extended interaction motif that also includes the two bulky C-terminal residues of the short PIPKIgamma635 variant is necessary for beta2 appendage engagement. The clathrin heavy chain accesses the same contact surface on the AP-2 beta2 appendage, but because of additional clathrin binding sites located within the unstructured hinge segment of the beta2 subunit, clathrin binds the beta2 chain with a higher apparent affinity than PIPKIgamma661. A clathrin-regulated interaction with AP-2 could allow PIPKIgamma661 to be strategically positioned for regional PtdIns(4,5)P(2) generation during clathrin-coated vesicle assembly at the synapse.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADP-Ribosylation Factors / genetics
  • ADP-Ribosylation Factors / metabolism
  • Adaptor Protein Complex 2 / genetics
  • Adaptor Protein Complex 2 / metabolism*
  • Alternative Splicing / physiology
  • Animals
  • Clathrin / genetics
  • Clathrin / metabolism*
  • Clathrin-Coated Vesicles / genetics
  • Clathrin-Coated Vesicles / metabolism*
  • Mice
  • Phosphatidylinositol 4,5-Diphosphate
  • Phosphotransferases (Alcohol Group Acceptor) / genetics
  • Phosphotransferases (Alcohol Group Acceptor) / metabolism*
  • Protein Structure, Tertiary / physiology
  • Protein Subunits / genetics
  • Protein Subunits / metabolism
  • Rats
  • Synaptosomes / metabolism*


  • Adaptor Protein Complex 2
  • Clathrin
  • Phosphatidylinositol 4,5-Diphosphate
  • Protein Subunits
  • Phosphotransferases (Alcohol Group Acceptor)
  • 1-phosphatidylinositol-4-phosphate 5-kinase
  • ADP-Ribosylation Factors