Abstract
Certain members of the Bcl-2 family inhibit apoptosis while others facilitate this physiological process of cell death. An expression screen for proteins that bind to Bcl-2 yielded a small novel protein, denoted Bim, whose only similarity to any known protein is the short (nine amino acid) BH3 motif shared by most Bcl-2 homologues. Bim provokes apoptosis, and the BH3 region is required for Bcl-2 binding and for most of its cytotoxicity. Like Bcl-2, Bim possesses a hydrophobic C-terminus and localizes to intracytoplasmic membranes. Three Bim isoforms, probably generated by alternative splicing, all induce apoptosis, the shortest being the most potent. Wild-type Bcl-2 associates with Bim in vivo and modulates its death function, whereas Bcl-2 mutants that lack survival function do neither. Significantly, Bcl-xL and Bcl-w, the two closest homologues of Bcl-2, also bind to Bim and inhibit its activity, but more distant viral homologues, adenovirus E1B19K and Epstein-Barr virus BHRF-1, can do neither. Hence, Bim appears to act as a 'death ligand' which can only neutralize certain members of the pro-survival Bcl-2 sub-family.
Full Text
The Full Text of this article is available as a PDF (699.8 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Altschul S. F., Gish W., Miller W., Myers E. W., Lipman D. J. Basic local alignment search tool. J Mol Biol. 1990 Oct 5;215(3):403–410. doi: 10.1016/S0022-2836(05)80360-2. [DOI] [PubMed] [Google Scholar]
- Blanar M. A., Rutter W. J. Interaction cloning: identification of a helix-loop-helix zipper protein that interacts with c-Fos. Science. 1992 May 15;256(5059):1014–1018. doi: 10.1126/science.1589769. [DOI] [PubMed] [Google Scholar]
- Boise L. H., González-García M., Postema C. E., Ding L., Lindsten T., Turka L. A., Mao X., Nuñez G., Thompson C. B. bcl-x, a bcl-2-related gene that functions as a dominant regulator of apoptotic cell death. Cell. 1993 Aug 27;74(4):597–608. doi: 10.1016/0092-8674(93)90508-n. [DOI] [PubMed] [Google Scholar]
- Boise L. H., Minn A. J., Noel P. J., June C. H., Accavitti M. A., Lindsten T., Thompson C. B. CD28 costimulation can promote T cell survival by enhancing the expression of Bcl-XL. Immunity. 1995 Jul;3(1):87–98. doi: 10.1016/1074-7613(95)90161-2. [DOI] [PubMed] [Google Scholar]
- Borner C., Martinou I., Mattmann C., Irmler M., Schaerer E., Martinou J. C., Tschopp J. The protein bcl-2 alpha does not require membrane attachment, but two conserved domains to suppress apoptosis. J Cell Biol. 1994 Aug;126(4):1059–1068. doi: 10.1083/jcb.126.4.1059. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Boyd J. M., Gallo G. J., Elangovan B., Houghton A. B., Malstrom S., Avery B. J., Ebb R. G., Subramanian T., Chittenden T., Lutz R. J. Bik, a novel death-inducing protein shares a distinct sequence motif with Bcl-2 family proteins and interacts with viral and cellular survival-promoting proteins. Oncogene. 1995 Nov 2;11(9):1921–1928. [PubMed] [Google Scholar]
- Bump N. J., Hackett M., Hugunin M., Seshagiri S., Brady K., Chen P., Ferenz C., Franklin S., Ghayur T., Li P. Inhibition of ICE family proteases by baculovirus antiapoptotic protein p35. Science. 1995 Sep 29;269(5232):1885–1888. doi: 10.1126/science.7569933. [DOI] [PubMed] [Google Scholar]
- Cheng E. H., Levine B., Boise L. H., Thompson C. B., Hardwick J. M. Bax-independent inhibition of apoptosis by Bcl-XL. Nature. 1996 Feb 8;379(6565):554–556. doi: 10.1038/379554a0. [DOI] [PubMed] [Google Scholar]
- Chinnaiyan A. M., O'Rourke K., Lane B. R., Dixit V. M. Interaction of CED-4 with CED-3 and CED-9: a molecular framework for cell death. Science. 1997 Feb 21;275(5303):1122–1126. doi: 10.1126/science.275.5303.1122. [DOI] [PubMed] [Google Scholar]
- Chittenden T., Flemington C., Houghton A. B., Ebb R. G., Gallo G. J., Elangovan B., Chinnadurai G., Lutz R. J. A conserved domain in Bak, distinct from BH1 and BH2, mediates cell death and protein binding functions. EMBO J. 1995 Nov 15;14(22):5589–5596. doi: 10.1002/j.1460-2075.1995.tb00246.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chittenden T., Harrington E. A., O'Connor R., Flemington C., Lutz R. J., Evan G. I., Guild B. C. Induction of apoptosis by the Bcl-2 homologue Bak. Nature. 1995 Apr 20;374(6524):733–736. doi: 10.1038/374733a0. [DOI] [PubMed] [Google Scholar]
- Cory S. Regulation of lymphocyte survival by the bcl-2 gene family. Annu Rev Immunol. 1995;13:513–543. doi: 10.1146/annurev.iy.13.040195.002501. [DOI] [PubMed] [Google Scholar]
- Farrow S. N., White J. H., Martinou I., Raven T., Pun K. T., Grinham C. J., Martinou J. C., Brown R. Cloning of a bcl-2 homologue by interaction with adenovirus E1B 19K. Nature. 1995 Apr 20;374(6524):731–733. doi: 10.1038/374731a0. [DOI] [PubMed] [Google Scholar]
- Feng D. F., Doolittle R. F. Progressive sequence alignment as a prerequisite to correct phylogenetic trees. J Mol Evol. 1987;25(4):351–360. doi: 10.1007/BF02603120. [DOI] [PubMed] [Google Scholar]
- Gibson L., Holmgreen S. P., Huang D. C., Bernard O., Copeland N. G., Jenkins N. A., Sutherland G. R., Baker E., Adams J. M., Cory S. bcl-w, a novel member of the bcl-2 family, promotes cell survival. Oncogene. 1996 Aug 15;13(4):665–675. [PubMed] [Google Scholar]
- Grussenmeyer T., Scheidtmann K. H., Hutchinson M. A., Eckhart W., Walter G. Complexes of polyoma virus medium T antigen and cellular proteins. Proc Natl Acad Sci U S A. 1985 Dec;82(23):7952–7954. doi: 10.1073/pnas.82.23.7952. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Han J., Sabbatini P., White E. Induction of apoptosis by human Nbk/Bik, a BH3-containing protein that interacts with E1B 19K. Mol Cell Biol. 1996 Oct;16(10):5857–5864. doi: 10.1128/mcb.16.10.5857. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hanada M., Aimé-Sempé C., Sato T., Reed J. C. Structure-function analysis of Bcl-2 protein. Identification of conserved domains important for homodimerization with Bcl-2 and heterodimerization with Bax. J Biol Chem. 1995 May 19;270(20):11962–11969. doi: 10.1074/jbc.270.20.11962. [DOI] [PubMed] [Google Scholar]
- Henderson S., Huen D., Rowe M., Dawson C., Johnson G., Rickinson A. Epstein-Barr virus-coded BHRF1 protein, a viral homologue of Bcl-2, protects human B cells from programmed cell death. Proc Natl Acad Sci U S A. 1993 Sep 15;90(18):8479–8483. doi: 10.1073/pnas.90.18.8479. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hengartner M. O., Horvitz H. R. Programmed cell death in Caenorhabditis elegans. Curr Opin Genet Dev. 1994 Aug;4(4):581–586. doi: 10.1016/0959-437x(94)90076-f. [DOI] [PubMed] [Google Scholar]
- Horton R. M., Ho S. N., Pullen J. K., Hunt H. D., Cai Z., Pease L. R. Gene splicing by overlap extension. Methods Enzymol. 1993;217:270–279. doi: 10.1016/0076-6879(93)17067-f. [DOI] [PubMed] [Google Scholar]
- Hsu Y. T., Wolter K. G., Youle R. J. Cytosol-to-membrane redistribution of Bax and Bcl-X(L) during apoptosis. Proc Natl Acad Sci U S A. 1997 Apr 15;94(8):3668–3672. doi: 10.1073/pnas.94.8.3668. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Huang D. C., Cory S., Strasser A. Bcl-2, Bcl-XL and adenovirus protein E1B19kD are functionally equivalent in their ability to inhibit cell death. Oncogene. 1997 Jan 30;14(4):405–414. doi: 10.1038/sj.onc.1200848. [DOI] [PubMed] [Google Scholar]
- Huang D. C., O'Reilly L. A., Strasser A., Cory S. The anti-apoptosis function of Bcl-2 can be genetically separated from its inhibitory effect on cell cycle entry. EMBO J. 1997 Aug 1;16(15):4628–4638. doi: 10.1093/emboj/16.15.4628. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Imaizumi K., Tsuda M., Imai Y., Wanaka A., Takagi T., Tohyama M. Molecular cloning of a novel polypeptide, DP5, induced during programmed neuronal death. J Biol Chem. 1997 Jul 25;272(30):18842–18848. doi: 10.1074/jbc.272.30.18842. [DOI] [PubMed] [Google Scholar]
- Inohara N., Ding L., Chen S., Núez G. harakiri, a novel regulator of cell death, encodes a protein that activates apoptosis and interacts selectively with survival-promoting proteins Bcl-2 and Bcl-X(L). EMBO J. 1997 Apr 1;16(7):1686–1694. doi: 10.1093/emboj/16.7.1686. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jacobson M. D. Apoptosis: Bcl-2-related proteins get connected. Curr Biol. 1997 May 1;7(5):R277–R281. doi: 10.1016/s0960-9822(06)00136-9. [DOI] [PubMed] [Google Scholar]
- Jacobson M. D., Weil M., Raff M. C. Programmed cell death in animal development. Cell. 1997 Feb 7;88(3):347–354. doi: 10.1016/s0092-8674(00)81873-5. [DOI] [PubMed] [Google Scholar]
- James C., Gschmeissner S., Fraser A., Evan G. I. CED-4 induces chromatin condensation in Schizosaccharomyces pombe and is inhibited by direct physical association with CED-9. Curr Biol. 1997 Apr 1;7(4):246–252. doi: 10.1016/s0960-9822(06)00120-5. [DOI] [PubMed] [Google Scholar]
- Kerr J. F., Wyllie A. H., Currie A. R. Apoptosis: a basic biological phenomenon with wide-ranging implications in tissue kinetics. Br J Cancer. 1972 Aug;26(4):239–257. doi: 10.1038/bjc.1972.33. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kiefer M. C., Brauer M. J., Powers V. C., Wu J. J., Umansky S. R., Tomei L. D., Barr P. J. Modulation of apoptosis by the widely distributed Bcl-2 homologue Bak. Nature. 1995 Apr 20;374(6524):736–739. doi: 10.1038/374736a0. [DOI] [PubMed] [Google Scholar]
- Knudson C. M., Korsmeyer S. J. Bcl-2 and Bax function independently to regulate cell death. Nat Genet. 1997 Aug;16(4):358–363. doi: 10.1038/ng0897-358. [DOI] [PubMed] [Google Scholar]
- Korsmeyer S. J. Regulators of cell death. Trends Genet. 1995 Mar;11(3):101–105. doi: 10.1016/S0168-9525(00)89010-1. [DOI] [PubMed] [Google Scholar]
- Kozopas K. M., Yang T., Buchan H. L., Zhou P., Craig R. W. MCL1, a gene expressed in programmed myeloid cell differentiation, has sequence similarity to BCL2. Proc Natl Acad Sci U S A. 1993 Apr 15;90(8):3516–3520. doi: 10.1073/pnas.90.8.3516. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Krajewski S., Tanaka S., Takayama S., Schibler M. J., Fenton W., Reed J. C. Investigation of the subcellular distribution of the bcl-2 oncoprotein: residence in the nuclear envelope, endoplasmic reticulum, and outer mitochondrial membranes. Cancer Res. 1993 Oct 1;53(19):4701–4714. [PubMed] [Google Scholar]
- Kroemer G. The proto-oncogene Bcl-2 and its role in regulating apoptosis. Nat Med. 1997 Jun;3(6):614–620. doi: 10.1038/nm0697-614. [DOI] [PubMed] [Google Scholar]
- Lin E. Y., Orlofsky A., Berger M. S., Prystowsky M. B. Characterization of A1, a novel hemopoietic-specific early-response gene with sequence similarity to bcl-2. J Immunol. 1993 Aug 15;151(4):1979–1988. [PubMed] [Google Scholar]
- Lithgow T., van Driel R., Bertram J. F., Strasser A. The protein product of the oncogene bcl-2 is a component of the nuclear envelope, the endoplasmic reticulum, and the outer mitochondrial membrane. Cell Growth Differ. 1994 Apr;5(4):411–417. [PubMed] [Google Scholar]
- Miyashita T., Krajewski S., Krajewska M., Wang H. G., Lin H. K., Liebermann D. A., Hoffman B., Reed J. C. Tumor suppressor p53 is a regulator of bcl-2 and bax gene expression in vitro and in vivo. Oncogene. 1994 Jun;9(6):1799–1805. [PubMed] [Google Scholar]
- Monaghan P., Robertson D., Amos T. A., Dyer M. J., Mason D. Y., Greaves M. F. Ultrastructural localization of bcl-2 protein. J Histochem Cytochem. 1992 Dec;40(12):1819–1825. doi: 10.1177/40.12.1453000. [DOI] [PubMed] [Google Scholar]
- Muchmore S. W., Sattler M., Liang H., Meadows R. P., Harlan J. E., Yoon H. S., Nettesheim D., Chang B. S., Thompson C. B., Wong S. L. X-ray and NMR structure of human Bcl-xL, an inhibitor of programmed cell death. Nature. 1996 May 23;381(6580):335–341. doi: 10.1038/381335a0. [DOI] [PubMed] [Google Scholar]
- Nicholson D. W., Thornberry N. A. Caspases: killer proteases. Trends Biochem Sci. 1997 Aug;22(8):299–306. doi: 10.1016/s0968-0004(97)01085-2. [DOI] [PubMed] [Google Scholar]
- Nicoletti I., Migliorati G., Pagliacci M. C., Grignani F., Riccardi C. A rapid and simple method for measuring thymocyte apoptosis by propidium iodide staining and flow cytometry. J Immunol Methods. 1991 Jun 3;139(2):271–279. doi: 10.1016/0022-1759(91)90198-o. [DOI] [PubMed] [Google Scholar]
- O'Reilly L. A., Huang D. C., Strasser A. The cell death inhibitor Bcl-2 and its homologues influence control of cell cycle entry. EMBO J. 1996 Dec 16;15(24):6979–6990. [PMC free article] [PubMed] [Google Scholar]
- Oltvai Z. N., Korsmeyer S. J. Checkpoints of dueling dimers foil death wishes. Cell. 1994 Oct 21;79(2):189–192. doi: 10.1016/0092-8674(94)90188-0. [DOI] [PubMed] [Google Scholar]
- Oltvai Z. N., Milliman C. L., Korsmeyer S. J. Bcl-2 heterodimerizes in vivo with a conserved homolog, Bax, that accelerates programmed cell death. Cell. 1993 Aug 27;74(4):609–619. doi: 10.1016/0092-8674(93)90509-o. [DOI] [PubMed] [Google Scholar]
- Orth K., O'Rourke K., Salvesen G. S., Dixit V. M. Molecular ordering of apoptotic mammalian CED-3/ICE-like proteases. J Biol Chem. 1996 Aug 30;271(35):20977–20980. doi: 10.1074/jbc.271.35.20977. [DOI] [PubMed] [Google Scholar]
- Pezzella F., Tse A. G., Cordell J. L., Pulford K. A., Gatter K. C., Mason D. Y. Expression of the bcl-2 oncogene protein is not specific for the 14;18 chromosomal translocation. Am J Pathol. 1990 Aug;137(2):225–232. [PMC free article] [PubMed] [Google Scholar]
- Reed J. C. Double identity for proteins of the Bcl-2 family. Nature. 1997 Jun 19;387(6635):773–776. doi: 10.1038/42867. [DOI] [PubMed] [Google Scholar]
- Sattler M., Liang H., Nettesheim D., Meadows R. P., Harlan J. E., Eberstadt M., Yoon H. S., Shuker S. B., Chang B. S., Minn A. J. Structure of Bcl-xL-Bak peptide complex: recognition between regulators of apoptosis. Science. 1997 Feb 14;275(5302):983–986. doi: 10.1126/science.275.5302.983. [DOI] [PubMed] [Google Scholar]
- Sedlak T. W., Oltvai Z. N., Yang E., Wang K., Boise L. H., Thompson C. B., Korsmeyer S. J. Multiple Bcl-2 family members demonstrate selective dimerizations with Bax. Proc Natl Acad Sci U S A. 1995 Aug 15;92(17):7834–7838. doi: 10.1073/pnas.92.17.7834. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sentman C. L., Shutter J. R., Hockenbery D., Kanagawa O., Korsmeyer S. J. bcl-2 inhibits multiple forms of apoptosis but not negative selection in thymocytes. Cell. 1991 Nov 29;67(5):879–888. doi: 10.1016/0092-8674(91)90361-2. [DOI] [PubMed] [Google Scholar]
- Seshagiri S., Miller L. K. Caenorhabditis elegans CED-4 stimulates CED-3 processing and CED-3-induced apoptosis. Curr Biol. 1997 Jul 1;7(7):455–460. doi: 10.1016/s0960-9822(06)00216-8. [DOI] [PubMed] [Google Scholar]
- Simonian P. L., Grillot D. A., Merino R., Nuñez G. Bax can antagonize Bcl-XL during etoposide and cisplatin-induced cell death independently of its heterodimerization with Bcl-XL. J Biol Chem. 1996 Sep 13;271(37):22764–22772. doi: 10.1074/jbc.271.37.22764. [DOI] [PubMed] [Google Scholar]
- Spector M. S., Desnoyers S., Hoeppner D. J., Hengartner M. O. Interaction between the C. elegans cell-death regulators CED-9 and CED-4. Nature. 1997 Feb 13;385(6617):653–656. doi: 10.1038/385653a0. [DOI] [PubMed] [Google Scholar]
- Srinivasula S. M., Ahmad M., Fernandes-Alnemri T., Litwack G., Alnemri E. S. Molecular ordering of the Fas-apoptotic pathway: the Fas/APO-1 protease Mch5 is a CrmA-inhibitable protease that activates multiple Ced-3/ICE-like cysteine proteases. Proc Natl Acad Sci U S A. 1996 Dec 10;93(25):14486–14491. doi: 10.1073/pnas.93.25.14486. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Strasser A., Harris A. W., Cory S. bcl-2 transgene inhibits T cell death and perturbs thymic self-censorship. Cell. 1991 Nov 29;67(5):889–899. doi: 10.1016/0092-8674(91)90362-3. [DOI] [PubMed] [Google Scholar]
- Strasser A., Harris A. W., Huang D. C., Krammer P. H., Cory S. Bcl-2 and Fas/APO-1 regulate distinct pathways to lymphocyte apoptosis. EMBO J. 1995 Dec 15;14(24):6136–6147. doi: 10.1002/j.1460-2075.1995.tb00304.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Strasser A., Harris A. W., Jacks T., Cory S. DNA damage can induce apoptosis in proliferating lymphoid cells via p53-independent mechanisms inhibitable by Bcl-2. Cell. 1994 Oct 21;79(2):329–339. doi: 10.1016/0092-8674(94)90201-1. [DOI] [PubMed] [Google Scholar]
- Vaux D. L., Cory S., Adams J. M. Bcl-2 gene promotes haemopoietic cell survival and cooperates with c-myc to immortalize pre-B cells. Nature. 1988 Sep 29;335(6189):440–442. doi: 10.1038/335440a0. [DOI] [PubMed] [Google Scholar]
- Veis D. J., Sentman C. L., Bach E. A., Korsmeyer S. J. Expression of the Bcl-2 protein in murine and human thymocytes and in peripheral T lymphocytes. J Immunol. 1993 Sep 1;151(5):2546–2554. [PubMed] [Google Scholar]
- Wang K., Yin X. M., Chao D. T., Milliman C. L., Korsmeyer S. J. BID: a novel BH3 domain-only death agonist. Genes Dev. 1996 Nov 15;10(22):2859–2869. doi: 10.1101/gad.10.22.2859. [DOI] [PubMed] [Google Scholar]
- White E. Life, death, and the pursuit of apoptosis. Genes Dev. 1996 Jan 1;10(1):1–15. doi: 10.1101/gad.10.1.1. [DOI] [PubMed] [Google Scholar]
- White E., Sabbatini P., Debbas M., Wold W. S., Kusher D. I., Gooding L. R. The 19-kilodalton adenovirus E1B transforming protein inhibits programmed cell death and prevents cytolysis by tumor necrosis factor alpha. Mol Cell Biol. 1992 Jun;12(6):2570–2580. doi: 10.1128/mcb.12.6.2570. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wu D., Wallen H. D., Nuñez G. Interaction and regulation of subcellular localization of CED-4 by CED-9. Science. 1997 Feb 21;275(5303):1126–1129. doi: 10.1126/science.275.5303.1126. [DOI] [PubMed] [Google Scholar]
- Xiang J., Chao D. T., Korsmeyer S. J. BAX-induced cell death may not require interleukin 1 beta-converting enzyme-like proteases. Proc Natl Acad Sci U S A. 1996 Dec 10;93(25):14559–14563. doi: 10.1073/pnas.93.25.14559. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Xue D., Horvitz H. R. Inhibition of the Caenorhabditis elegans cell-death protease CED-3 by a CED-3 cleavage site in baculovirus p35 protein. Nature. 1995 Sep 21;377(6546):248–251. doi: 10.1038/377248a0. [DOI] [PubMed] [Google Scholar]
- Yang E., Zha J., Jockel J., Boise L. H., Thompson C. B., Korsmeyer S. J. Bad, a heterodimeric partner for Bcl-XL and Bcl-2, displaces Bax and promotes cell death. Cell. 1995 Jan 27;80(2):285–291. doi: 10.1016/0092-8674(95)90411-5. [DOI] [PubMed] [Google Scholar]
- Yin X. M., Oltvai Z. N., Korsmeyer S. J. BH1 and BH2 domains of Bcl-2 are required for inhibition of apoptosis and heterodimerization with Bax. Nature. 1994 May 26;369(6478):321–323. doi: 10.1038/369321a0. [DOI] [PubMed] [Google Scholar]
- Yuan J., Horvitz H. R. The Caenorhabditis elegans cell death gene ced-4 encodes a novel protein and is expressed during the period of extensive programmed cell death. Development. 1992 Oct;116(2):309–320. doi: 10.1242/dev.116.2.309. [DOI] [PubMed] [Google Scholar]
- Zha H., Aimé-Sempé C., Sato T., Reed J. C. Proapoptotic protein Bax heterodimerizes with Bcl-2 and homodimerizes with Bax via a novel domain (BH3) distinct from BH1 and BH2. J Biol Chem. 1996 Mar 29;271(13):7440–7444. doi: 10.1074/jbc.271.13.7440. [DOI] [PubMed] [Google Scholar]
- Zou H., Henzel W. J., Liu X., Lutschg A., Wang X. Apaf-1, a human protein homologous to C. elegans CED-4, participates in cytochrome c-dependent activation of caspase-3. Cell. 1997 Aug 8;90(3):405–413. doi: 10.1016/s0092-8674(00)80501-2. [DOI] [PubMed] [Google Scholar]
- von Freeden-Jeffry U., Solvason N., Howard M., Murray R. The earliest T lineage-committed cells depend on IL-7 for Bcl-2 expression and normal cell cycle progression. Immunity. 1997 Jul;7(1):147–154. doi: 10.1016/s1074-7613(00)80517-8. [DOI] [PubMed] [Google Scholar]