A ligand-induced extracellular cleavage regulates gamma-secretase-like proteolytic activation of Notch1

Mol Cell. 2000 Feb;5(2):197-206. doi: 10.1016/s1097-2765(00)80416-5.


Gamma-secretase-like proteolysis at site 3 (S3), within the transmembrane domain, releases the Notch intracellular domain (NICD) and activates CSL-mediated Notch signaling. S3 processing occurs only in response to ligand binding; however, the molecular basis of this regulation is unknown. Here we demonstrate that ligand binding facilitates cleavage at a novel site (S2), within the extracellular juxtamembrane region, which serves to release ectodomain repression of NICD production. Cleavage at S2 generates a transient intermediate peptide termed NEXT (Notch extracellular truncation). NEXT accumulates when NICD production is blocked by point mutations or gamma-secretase inhibitors or by loss of presenilin 1, and inhibition of NEXT eliminates NICD production. Our data demonstrate that S2 cleavage is a ligand-regulated step in the proteolytic cascade leading to Notch activation.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Amyloid Precursor Protein Secretases
  • Conserved Sequence
  • Cysteine / genetics
  • Disintegrins / metabolism
  • Drosophila Proteins*
  • Endopeptidases / metabolism*
  • Ligands
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Metalloendopeptidases / metabolism
  • Mutation
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism*
  • Presenilin-1
  • Protein Processing, Post-Translational*
  • Receptor, Notch1
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism*
  • Signal Transduction
  • Transcription Factors*


  • Disintegrins
  • Drosophila Proteins
  • Ligands
  • Membrane Proteins
  • Peptide Fragments
  • Presenilin-1
  • Receptor, Notch1
  • Receptors, Cell Surface
  • Transcription Factors
  • Amyloid Precursor Protein Secretases
  • Endopeptidases
  • KUZ protein, Drosophila
  • Metalloendopeptidases
  • Cysteine