3v6a
Helical repeat structure of apoptosis inhibitor 5 reveals protein-protein interaction modules
Structural highlights
FunctionAPI5_HUMAN Antiapoptotic factor that may have a role in protein assembly. Negatively regulates ACIN1. By binding to ACIN1, it suppresses ACIN1 cleavage from CASP3 and ACIN1-mediated DNA fragmentation. Also known to efficiently suppress E2F1-induced apoptosis. Its depletion enhances the cytotoxic action of the chemotherapeutic drugs.[1] [2] [3] Publication Abstract from PubMedApoptosis inhibitor 5 (API5) is an anti-apoptotic protein that is up-regulated in various cancer cells. Here, we present the crystal structure of human API5. API5 exhibits an elongated all alpha-helical structure. The N-terminal half of API5 is similar to the HEAT repeat and the C-terminal half is similar to the ARM (Armadillo-like) repeat. HEAT and ARM repeats have been implicated in protein-protein interactions, suggesting that the cellular roles of API5 may be to mediate protein-protein interactions. Various components of multiprotein complexes have been identified as API5-interacting protein partners, suggesting that API5 may act as a scaffold for multiprotein complexes. API5 exists as a monomer, and the functionally important heptad leucine repeat does not exhibit the predicted a dimeric leucine zipper. Additionally, Lys-251, which can be acetylated in cells, plays important roles in the inhibition of apoptosis under serum deprivation conditions. The acetylation of this lysine also affects the stability of API5 in cells. Helical repeat structure of apoptosis inhibitor 5 reveals protein-protein interaction modules.,Han BG, Kim KH, Lee SJ, Jeong KC, Cho JW, Noh KH, Kim TW, Kim SJ, Yoon HJ, Suh SW, Lee S, Lee BI J Biol Chem. 2012 Mar 30;287(14):10727-37. doi: 10.1074/jbc.M111.317594. Epub, 2012 Feb 12. PMID:22334682[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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