Molecular basis of the interaction between the antiapoptotic Bcl-2 family proteins and the proapoptotic protein ASPP2

Chen Katz, Hadar Benyamini, Shahar Rotem, Mario Lebendiker, Tsafi Danieli, Anat Iosub, Hadar Refaely, Monica Dines, Vered Bronner, Tsafrir Bravman, Deborah E. Shalev, Stefan Rüdiger, Assaf Friedler*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


We have characterized the molecular basis of the interaction between ASPP2 and Bcl-2, which are key proteins in the apoptotic pathway. The C-terminal ankyrin repeats and SH3 domain of ASPP2 (ASPP2Ank-SH3) mediate its interactions with the antiapoptotic protein Bcl-2. We used biophysical and computational methods to identify the interaction sites of Bcl-2 and its homologues with ASPP2. Using peptide array screening, we found that ASPP2 Ank-SH3 binds two homologous sites in all three Bcl proteins tested: (i) the conserved BH4 motif, and (ii) a binding site for proapoptotic regulators. Quantitative binding studies revealed that binding of ASPP2 Ank-SH3 to the Bcl-2 family members is selective at two levels: (i) interaction with Bcl-2-derived peptides is the tightest compared to peptides from the other family members, and (ii) within Bcl-2, binding of ASPP2 Ank-SH3 to the BH4 domain is tightest. Sequence alignment of the ASPP2-binding peptides combined with binding studies of mutated peptides revealed that two nonconserved positions where only Bcl-2 contains positively charged residues account for its tighter binding. The experimental binding results served as a basis for docking analysis, by which we modeled the complexes of ASPP2Ank-SH3 with the full-length Bcl proteins. Using peptide arrays and quantitative binding studies, we found that Bcl-2 binds three loops in ASPP2Ank-SH3 with similar affinity, in agreement with our predicted model. Based on our results, we propose a mechanism in which ASPP2 induces apoptosis by inhibiting functional sites of the antiapoptotic Bcl-2 proteins.

Original languageAmerican English
Pages (from-to)12277-12282
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number34
StatePublished - 26 Aug 2008


  • Apoptosis
  • Docking
  • Peptide arrays
  • Peptides
  • Protein-protein interactions


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