| Structural highlights
Function
[IF4G2_HUMAN] Appears to play a role in the switch from cap-dependent to IRES-mediated translation during mitosis, apoptosis and viral infection. Cleaved by some caspases and viral proteases.[1] [2] [3] [4]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
DAP5/p97 (death-associated protein 5) is a member of the eukaryotic translation initiation factor 4G family. It functions as a scaffold protein promoting cap-independent translation of proteins. During apoptosis, DAP5/p97 is cleaved by caspases at position 792, yielding an 86-kDa C-terminal truncated isoform (DAP5/p86) that promotes translation of several mRNAs mediated by an internal ribosome entry site. In this study, we report the crystal structure of the C-terminal region of DAP5/p97 extending between amino acids 730 and 897. This structure consists of four HEAT-Repeats and is homologous to the C-terminal domain of eIF4GI, eIF5, and eIF2Bepsilon. Unlike the other proteins, DAP5/p97 lacks electron density in the loop connecting alpha3 and alpha4, which harbors the caspase cleavage site. Moreover, we observe fewer interactions between these two helices. Thus, previous mapping of this site by mutation analysis is confirmed here by the resolved structure of the DAP5/p97 C-terminus. In addition, we identified the position of two conserved aromatic and acidic boxes in the structure of the DAP5/p97 C-terminus. The acidic residues in the two aromatic and acidic boxes form a continuous negatively charged patch, which is suggested to make specific interactions with other proteins such as eIF2beta. The caspase cleavage of DAP5/p97 removes the subdomain carrying acidic residues in the AA-box motif, which may result in exposure of a hydrophobic surface. These intriguing structural differences between the two DAP5 isoforms suggest that they have different interaction partners and, subsequently, different functions.
The Crystal Structure of the C-Terminal DAP5/p97 Domain Sheds Light on the Molecular Basis for Its Processing by Caspase Cleavage.,Liberman N, Dym O, Unger T, Albeck S, Peleg Y, Jacobovitch Y, Branzburg A, Eisenstein M, Marash L, Kimchi A J Mol Biol. 2008 Aug 12. PMID:18722383[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Imataka H, Olsen HS, Sonenberg N. A new translational regulator with homology to eukaryotic translation initiation factor 4G. EMBO J. 1997 Feb 17;16(4):817-25. PMID:9049310 doi:10.1093/emboj/16.4.817
- ↑ Levy-Strumpf N, Deiss LP, Berissi H, Kimchi A. DAP-5, a novel homolog of eukaryotic translation initiation factor 4G isolated as a putative modulator of gamma interferon-induced programmed cell death. Mol Cell Biol. 1997 Mar;17(3):1615-25. PMID:9032289
- ↑ Pyronnet S, Dostie J, Sonenberg N. Suppression of cap-dependent translation in mitosis. Genes Dev. 2001 Aug 15;15(16):2083-93. PMID:11511540 doi:10.1101/gad.889201
- ↑ Henis-Korenblit S, Shani G, Sines T, Marash L, Shohat G, Kimchi A. The caspase-cleaved DAP5 protein supports internal ribosome entry site-mediated translation of death proteins. Proc Natl Acad Sci U S A. 2002 Apr 16;99(8):5400-5. Epub 2002 Apr 9. PMID:11943866 doi:10.1073/pnas.082102499
- ↑ Liberman N, Dym O, Unger T, Albeck S, Peleg Y, Jacobovitch Y, Branzburg A, Eisenstein M, Marash L, Kimchi A. The Crystal Structure of the C-Terminal DAP5/p97 Domain Sheds Light on the Molecular Basis for Its Processing by Caspase Cleavage. J Mol Biol. 2008 Aug 12. PMID:18722383 doi:S0022-2836(08)00993-5
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