Direct interaction of the 170 kDa isoform of synaptojanin 1 with clathrin and with the clathrin adaptor AP-2

Curr Biol. 2000 Apr 20;10(8):471-4. doi: 10.1016/s0960-9822(00)00446-2.


Synaptojanin 1, a polyphosphoinositide phosphatase, is expressed as two major alternatively spliced isoforms of 145 kDa (SJ145) and 170 kDa (SJ170) [1] [2], which are thought to have pleiotropic roles in endocytosis, signaling and actin function [3] [4] [5]. SJ145 is highly enriched in nerve terminals where it participates in clathrin-dependent synaptic vesicle recycling [1] [5]. SJ170, which differs from SJ145 by the presence of a carboxy-terminal extension, is the predominant isoform in developing neurons and is expressed in a variety of tissues [2]. The carboxy-terminal domain unique to SJ170 was previously shown to bind Eps15 [6], a protein involved in receptor-mediated endocytosis. Here, we show that the same domain also binds clathrin and the clathrin adaptor AP-2. These interactions occur both in vitro and in vivo and are direct. Binding of AP-2 is mediated by the ear domain of its alpha-adaptin subunit and binding of clathrin by the amino-terminal domain of its heavy chain. Overexpression in chinese hamster ovary (CHO) cells of full-length SJ170 or its unique carboxy-terminal region caused mislocalization of Eps15, AP-2 and clathrin, as well as inhibition of clathrin-dependent transferrin uptake. These findings suggest a close association of SJ170 with the clathrin coat and provide new evidence for its physiological role in the regulation of clathrin coat dynamics.

Publication types

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

MeSH terms

  • Adaptor Protein Complex alpha Subunits
  • Adaptor Proteins, Vesicular Transport
  • Animals
  • CHO Cells
  • Clathrin / metabolism*
  • Cricetinae
  • Humans
  • Immunoblotting
  • Isoenzymes / metabolism
  • Membrane Proteins / metabolism*
  • Nerve Tissue Proteins / chemistry
  • Nerve Tissue Proteins / metabolism*
  • PC12 Cells
  • Phosphoric Monoester Hydrolases / chemistry
  • Phosphoric Monoester Hydrolases / metabolism*
  • Rats
  • Transformation, Genetic


  • Adaptor Protein Complex alpha Subunits
  • Adaptor Proteins, Vesicular Transport
  • Clathrin
  • Isoenzymes
  • Membrane Proteins
  • Nerve Tissue Proteins
  • synaptojanin
  • Phosphoric Monoester Hydrolases