4cin
Complex of Bcl-xL with its BH3 domain
Structural highlights
FunctionB2CL1_HUMAN Potent inhibitor of cell death. Inhibits activation of caspases (By similarity). Appears to regulate cell death by blocking the voltage-dependent anion channel (VDAC) by binding to it and preventing the release of the caspase activator, CYC1, from the mitochondrial membrane. Also acts as a regulator of G2 checkpoint and progression to cytokinesis during mitosis.[1] [2] Isoform Bcl-X(S) promotes apoptosis.[3] [4] Publication Abstract from PubMedBcl-2 Homology 3 (BH3) domains are short sequence motifs that mediate nearly all protein-protein interactions between B cell lymphoma 2 (Bcl-2) family proteins in the intrinsic apoptotic cell death pathway. These sequences are found on both pro-survival and pro-apoptotic members even though their primary function is believed to be associated with induction of cell death. Here, we identify critical features of the BH3 domains of pro-survival proteins that distinguish them functionally from their pro-apoptotic counterparts. Biochemical and X-ray crystallographic studies demonstrate that these differences reduce the capacity of most pro-survival proteins to form high affinity "BH3-in-groove" complexes that are critical for cell death induction. Switching these residues for the corresponding residues in Bcl-2 homologous antagonist/killer (Bak) increases the binding affinity of isolated BH3 domains to pro-survival proteins, however, their exchange in the context of the parental protein causes rapid proteasomal degradation due to protein destabilization. This is supported by further X-ray crystallographic studies that capture elements of this destabilization in one pro-survival protein, Bcl-w. In pro-apoptotic Bak, we demonstrate that the corresponding distinguishing residues are important for its stability, cell-killing capacity, and antagonism by pro-survival proteins. The Functional Differences of Pro-survival and Pro-apoptotic B cell lymphoma 2 (Bcl-2) Proteins Depend on Structural Differences in their Bcl-2 Homology 3 (BH3) Domains.,Lee EF, Dewson G, Evangelista M, Pettikiriarachchi A, Zhu H, Colman PM, Fairlie WD J Biol Chem. 2014 Nov 3. pii: jbc.M114.610758. PMID:25371206[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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