Eukaryotic translation initiation factor 4E-binding protein 1 (also known as 4E-BP1) is a protein that in humans is encoded by the EIF4EBP1gene.[5] inhibits cap-dependent translation by binding to translation initiation factor eIF4E. Phosphorylation of 4E-BP1 results in its release from eIF4E, thereby allows cap-dependent translation to continue thereby increasing the rate of protein synthesis.[6]
Phosphorylation
Phosphorylated 4E-BP1 is thought to be a marker of upstream signaling (mTOR) activation. 4E-BP1 has seven phospho-sites, the three most important of which are the initiation site Thr 37/Thr 46, the second site Thr 70, and the final site Ser65. Moreover, phosphorylation of Ser 65 and Thr 70 alone was not sufficient to block the inhibition of mRNA translation by 4E-BP1, suggesting that multiple phosphorylation events must be combined to increase the rate of protein synthesis.[7]
Function
This gene encodes one member of a family of translation repressor proteins. The protein directly interacts with eukaryotic translation initiation factor 4E (eIF4E), which is a limiting component of the multisubunit complex that recruits 40S ribosomal subunits to the 5' end of mRNAs. Interaction of this protein with eIF4E inhibits complex assembly and represses translation. This protein is phosphorylated in response to various signals including UV irradiation and insulin signaling, resulting in its dissociation from eIF4E and activation of cap-dependent mRNA translation.[8]
High level of phosphorylated 4E-BP1 has been widely reported in human cancers, and is associated with a worse outcome in several malignancies.[9]
^"Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^"Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
^Pause A, Belsham GJ, Gingras AC, Donzé O, Lin TA, Lawrence JC, Sonenberg N (November 1994). "Insulin-dependent stimulation of protein synthesis by phosphorylation of a regulator of 5'-cap function". Nature. 371 (6500): 762–767. Bibcode:1994Natur.371..762P. doi:10.1038/371762a0. PMID7935836. S2CID4360955.
^Rual JF, Venkatesan K, Hao T, Hirozane-Kishikawa T, Dricot A, Li N, Berriz GF, Gibbons FD, Dreze M, Ayivi-Guedehoussou N, Klitgord N, Simon C, Boxem M, Milstein S, Rosenberg J, Goldberg DS, Zhang LV, Wong SL, Franklin G, Li S, Albala JS, Lim J, Fraughton C, Llamosas E, Cevik S, Bex C, Lamesch P, Sikorski RS, Vandenhaute J, Zoghbi HY, Smolyar A, Bosak S, Sequerra R, Doucette-Stamm L, Cusick ME, Hill DE, Roth FP, Vidal M (October 2005). "Towards a proteome-scale map of the human protein-protein interaction network". Nature. 437 (7062): 1173–8. Bibcode:2005Natur.437.1173R. doi:10.1038/nature04209. PMID16189514. S2CID4427026.
^Ewing RM, Chu P, Elisma F, Li H, Taylor P, Climie S, McBroom-Cerajewski L, Robinson MD, O'Connor L, Li M, Taylor R, Dharsee M, Ho Y, Heilbut A, Moore L, Zhang S, Ornatsky O, Bukhman YV, Ethier M, Sheng Y, Vasilescu J, Abu-Farha M, Lambert JP, Duewel HS, Stewart II, Kuehl B, Hogue K, Colwill K, Gladwish K, Muskat B, Kinach R, Adams SL, Moran MF, Morin GB, Topaloglou T, Figeys D (2007). "Large-scale mapping of human protein-protein interactions by mass spectrometry". Mol. Syst. Biol. 3: 89. doi:10.1038/msb4100134. PMC1847948. PMID17353931.
^Ha SH, Kim DH, Kim IS, Kim JH, Lee MN, Lee HJ, Kim JH, Jang SK, Suh PG, Ryu SH (December 2006). "PLD2 forms a functional complex with mTOR/raptor to transduce mitogenic signals". Cell. Signal. 18 (12): 2283–91. doi:10.1016/j.cellsig.2006.05.021. PMID16837165.
Rousseau D, Gingras AC, Pause A, Sonenberg N (1997). "The eIF4E-binding proteins 1 and 2 are negative regulators of cell growth". Oncogene. 13 (11): 2415–20. PMID8957083.
Tsukiyama-Kohara K, Vidal SM, Gingras AC, Glover TW, Hanash SM, Heng H, Sonenberg N (1997). "Tissue distribution, genomic structure, and chromosome mapping of mouse and human eukaryotic initiation factor 4E-binding proteins 1 and 2". Genomics. 38 (3): 353–363. doi:10.1006/geno.1996.0638. PMID8975712.
Seeley TW, Wang L, Zhen JY (1999). "Phosphorylation of human MAD1 by the BUB1 kinase in vitro". Biochem. Biophys. Res. Commun. 257 (2): 589–595. doi:10.1006/bbrc.1999.0514. PMID10198256.