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  • The EMBO Journal (2006) 25, 4215 - 4222
  • doi:10.1038/sj.emboj.7601308

Published online: 31 August 2006

Single-molecule analysis of epidermal growth factor binding on the surface of living cells

Yuji Teramura1, Junya Ichinose1, Hiroaki Takagi1, Kenji Nishida1, Toshio Yanagida1,2 and Yasushi Sako1,2,3

  1. Laboratories for Nanobiology, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
  2. Formation of Soft Nanomachines, CREST, JST, Suita, Osaka, Japan
  3. Cellular Informatics Laboratory, RIKEN, Wako, Saitama, Japan

Correspondence to:

Yasushi Sako, Laboratories for Nanobiology, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan. Tel.: +81 6 6879 4426; Fax: +81 6 6879 4427; E-mail: sako@phys1.med.osaka-u.ac.jp

Received 17 February 2006; Accepted 3 August 2006

Global cellular responses induced by epidermal growth factor (EGF) receptor (EGFR) occur immediately with a less than 1% occupancy among tens of thousands of EGFR molecules on single cell surface. Activation of EGFR requires the formation of a signaling dimer of EGFR bound with a single ligand to each molecule. How sufficient numbers of signaling dimers are formed at such low occupancy rate is still not known. Here, we have analyzed the kinetics of EGF binding and the formation of the signaling dimer using single-molecule imaging and mathematical modeling. A small number of EGFR on the cell surface formed dimeric binding sites, which bound EGF two orders of magnitude faster than the monomeric binding sites. There was a positive cooperative binding of EGF to the dimeric binding sites through a newly discovered kinetic intermediate. These two mechanisms facilitate the formation of signaling dimers of EGF/EGFR complexes.

  • Keywords:

    • dimerization,
    • EGF,
    • mathematical modeling,
    • signal transduction