Phosphorylation of Numb regulates its interaction with the clathrin-associated adaptor AP-2

Hiroshi Tokumitsu, Naoya Hatano, Shigeyuki Yokokura, Yuka Sueyoshi, Naohito Nozaki, Ryoji Kobayashi

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


Numb is thought to participate in clathrin-dependent endocytosis by directly interacting with the clathrin-associated adaptor complex AP-2, although the underlying mechanisms are unknown. Numb is also known to be phosphorylated at Ser264 in vitro and in vivo. Here, we found that Numb is phosphorylated in vitro by Ca2+/calmodulin-dependent protein kinase I on Ser283. This phosphorylation was also observed in transfected COS-7 cells, indicating its physiological relevance. Pull-down experiments showed that the phosphorylation of Numb impaired its binding to the AP-2 complex and simultaneously recruited 14-3-3 proteins in vitro. Based on experiments using Numb mutants, both the initial phosphorylation of Ser264 and the subsequent phosphorylation of Ser283 are sufficient to abolish the binding of Numb to AP-2 and to promote the interaction with 14-3-3 protein. These findings suggest a novel mechanism for the regulation of Numb-mediated endocytosis, namely through direct phosphorylation.

Original languageEnglish
Pages (from-to)5797-5801
Number of pages5
JournalFEBS Letters
Issue number24
Publication statusPublished - Oct 16 2006
Externally publishedYes


  • AP-2 complex
  • Endocytosis
  • Numb
  • Phosphorylation

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology


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