New Insights Into Apoptosome Structure and Function

Cell Death Differ. 2018 Jul;25(7):1194-1208. doi: 10.1038/s41418-017-0025-z. Epub 2018 May 15.


The apoptosome is a platform that activates apical procaspases in response to intrinsic cell death signals. Biochemical and structural studies in the past two decades have extended our understanding of apoptosome composition and structure, while illuminating the requirements for initiator procaspase activation. A number of studies have now provided high-resolution structures for apoptosomes from C. elegans (CED-4), D. melanogaster (Dark), and H. sapiens (Apaf-1), which define critical protein interfaces, including intra and interdomain interactions. This work also reveals interactions of apoptosomes with their respective initiator caspases, CED-3, Dronc and procaspase-9. Structures of the human apoptosome have defined the requirements for cytochrome c binding, which triggers the conversion of inactive Apaf-1 molecules to an extended, assembly competent state. While recent data have provided a detailed understanding of apoptosome formation and procaspase activation, they also highlight important evolutionary differences with functional implications for caspase activation. Comparison of the CARD/CARD disks and apoptosomes formed by CED-4, Dark and Apaf-1. Cartoons of the active states of the CARD-CARD disks, illustrating the two CED-4 CARD tetrameric ring layers (CED4a and CED4b; top row) and the binding of 8 Dronc CARDs and between 3-4 pc-9 CARDs, to the Dark and Apaf-1 CARD disk respectively (middle and lower rows). Ribbon diagrams of the active CED-4, Dark and Apaf-1 apoptosomes are shown (right column).

Publication types

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

MeSH terms

  • Animals
  • Apoptosomes / metabolism*
  • Apoptotic Protease-Activating Factor 1 / genetics
  • Apoptotic Protease-Activating Factor 1 / metabolism*
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Caspase 9 / genetics
  • Caspase 9 / metabolism*
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism*
  • Drosophila melanogaster
  • Humans


  • APAF1 protein, human
  • Apoptosomes
  • Apoptotic Protease-Activating Factor 1
  • Caenorhabditis elegans Proteins
  • Drosophila Proteins
  • CASP9 protein, human
  • Caspase 9