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Apoptotic peptidase activating factor 1
Rainbow colored cartoon diagram (N-terminus = blue, C-terminus = red) of the crystallographic structure of the CARD domain of human APAF1.[1]
Available structures
PDB Ortholog search: PDBe, RCSB
Symbols APAF1 ; APAF-1; CED4
External IDs OMIM602233 MGI1306796 HomoloGene7626 ChEMBL: 1795093 GeneCards: APAF1 Gene
RNA expression pattern
PBB GE APAF1 204859 s at tn.png
PBB GE APAF1 211553 x at tn.png
PBB GE APAF1 211554 s at tn.png
More reference expression data
Species Human Mouse
Entrez 317 11783
Ensembl ENSG00000120868 ENSMUSG00000019979
UniProt O14727 O88879
RefSeq (mRNA) NM_001160 NM_001042558
RefSeq (protein) NP_001151 NP_001036023
Location (UCSC) Chr 12:
98.65 – 98.74 Mb
Chr 10:
90.99 – 91.08 Mb
PubMed search [1] [2]

Apoptotic protease activating factor 1, also known as APAF1, is a human homolog of C. elegans CED-4 gene.[2][3][4] APAF-1 and CED-4 homologs have been found in all currently sequenced animal genomes.


This gene encodes a cytoplasmic protein that forms one of the central hubs in the apoptosis regulatory network. This protein contains (from the N terminal) a caspase recruitment domain (CARD), an ATPase domain (NB-ARC), few short helical domains and then several copies of the WD40 repeat domain. Upon binding cytochrome c and dATP, this protein forms an oligomeric apoptosome. The apoptosome binds and cleaves Procaspase 9 protein, releasing its mature, activated form. The precise mechanism for this reaction is still debated though work published by Guy Salvesen suggests that the apoptosome may induce caspase 9 dimerization and subsequent autocatalysis.[5] Activated caspase 9 stimulates the subsequent caspase cascade that commits the cell to apoptosis.

Alternative splicing results in several transcript variants encoding different isoforms.[2]


The first crystal structure of the first two (CARD and NB-ARC) domains of the Apaf-1 protein PDB: 1z6t  was solved in the laboratory of Yigong Shi.[6] It contains a CARD domain with a Greek key motif composed of six helices, a Rossman fold nucleotide binding domains, a short helical motif and a winged-helix domain.


The Apaf-1 protein was identified by Xiaodong Wang.[3]


APAF1 has been shown to interact with NLRP1,[7] Caspase-9,[7][8][9][10][11] APIP,[8] BCL2-like 1[10][11] and HSPA4.[12]


  1. ^ PDB: 2p1h ; Milam SL, Nicely NI, Feeney B, Mattos C, Clark AC (May 2007). "Rapid folding and unfolding of Apaf-1 CARD". J. Mol. Biol. 369 (1): 290–304. doi:10.1016/j.jmb.2007.02.105. PMC 2020445. PMID 17408690. 
  2. ^ a b "Entrez Gene: APAF1 apoptotic peptidase activating factor 1". 
  3. ^ a b Zou H, Henzel WJ, Liu X, Lutschg A, Wang X (August 1997). "Apaf-1, a human protein homologous to C. elegans CED-4, participates in cytochrome c-dependent activation of caspase-3". Cell 90 (3): 405–13. doi:10.1016/S0092-8674(00)80501-2. PMID 9267021. 
  4. ^ Kim H, Jung YK, Kwon YK, Park SH (1999). "Assignment of apoptotic protease activating factor-1 gene (APAF1) to human chromosome band 12q23 by fluorescence in situ hybridization". Cytogenet. Cell Genet. 87 (3-4): 252–3. doi:10.1159/000015436. PMID 10702682. 
  5. ^ Pop C, Timmer J, Sperandio S, Salvesen GS (April 2006). "The apoptosome activates caspase-9 by dimerization". Mol. Cell 22 (2): 269–75. doi:10.1016/j.molcel.2006.03.009. PMID 16630894. 
  6. ^ Riedl SJ, Li W, Chao Y, Schwarzenbacher R, Shi Y (April 2005). "Structure of the apoptotic protease-activating factor 1 bound to ADP". Nature 434 (7035): 926–33. doi:10.1038/nature03465. PMID 15829969. 
  7. ^ a b Chu, Z L; Pio F; Xie Z; Welsh K; Krajewska M; Krajewski S; Godzik A; Reed J C (March 2001). "A novel enhancer of the Apaf1 apoptosome involved in cytochrome c-dependent caspase activation and apoptosis". J. Biol. Chem. (United States) 276 (12): 9239–45. doi:10.1074/jbc.M006309200. ISSN 0021-9258. PMID 11113115. 
  8. ^ a b Cho, Dong-Hyung; Hong Yeon-Mi; Lee Ho-June; Woo Ha-Na; Pyo Jong-Ok; Mak Tak W; Jung Yong-Keun (September 2004). "Induced inhibition of ischemic/hypoxic injury by APIP, a novel Apaf-1-interacting protein". J. Biol. Chem. (United States) 279 (38): 39942–50. doi:10.1074/jbc.M405747200. ISSN 0021-9258. PMID 15262985. 
  9. ^ Li, P; Nijhawan D; Budihardjo I; Srinivasula S M; Ahmad M; Alnemri E S; Wang X (November 1997). "Cytochrome c and dATP-dependent formation of Apaf-1/caspase-9 complex initiates an apoptotic protease cascade". Cell (UNITED STATES) 91 (4): 479–89. doi:10.1016/S0092-8674(00)80434-1. ISSN 0092-8674. PMID 9390557. 
  10. ^ a b Hu, Y; Benedict M A; Wu D; Inohara N; Núñez G (April 1998). "Bcl-XL interacts with Apaf-1 and inhibits Apaf-1-dependent caspase-9 activation". Proc. Natl. Acad. Sci. U.S.A. (UNITED STATES) 95 (8): 4386–91. doi:10.1073/pnas.95.8.4386. ISSN 0027-8424. PMC 22498. PMID 9539746. 
  11. ^ a b Pan, G; O'Rourke K; Dixit V M (March 1998). "Caspase-9, Bcl-XL, and Apaf-1 form a ternary complex". J. Biol. Chem. (UNITED STATES) 273 (10): 5841–5. doi:10.1074/jbc.273.10.5841. ISSN 0021-9258. PMID 9488720. 
  12. ^ Saleh, A; Srinivasula S M; Balkir L; Robbins P D; Alnemri E S (August 2000). "Negative regulation of the Apaf-1 apoptosome by Hsp70". Nat. Cell Biol. (ENGLAND) 2 (8): 476–83. doi:10.1038/35019510. ISSN 1465-7392. PMID 10934467. 

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