EIF4E
Description
The EIF4E (eukaryotic translation initiation factor 4E) is a protein-coding gene located on chromosome 4.
Eukaryotic translation initiation factor 4E, also known as eIF4E, is a protein that in humans is encoded by the EIF4E gene.
== Structure and function == Most eukaryotic cellular mRNAs are blocked at their 5'-ends with the 7-methyl-guanosine five-prime cap structure, m7GpppX (where X is any nucleotide). This structure is involved in several cellular processes including enhanced translational efficiency, splicing, mRNA stability, and RNA nuclear export. eIF4E is a eukaryotic translation initiation factor involved in directing ribosomes to the cap structure of mRNAs as well as other steps in RNA metabolism that require cap-binding. It is a 24-kD polypeptide that exists as both a free form and as part of the eIF4F pre-initiation complex. Many cellular mRNAs require eIF4E in order to be translated into protein. The eIF4E polypeptide is considered by some to be the rate-limiting component of the eukaryotic translation apparatus and is involved in the mRNA-ribosome binding step of eukaryotic protein synthesis. The other subunits of eIF4F are a 47-kD polypeptide, termed eIF4A, that possesses ATPase and RNA helicase activities, and a 220-kD scaffolding polypeptide, eIF4G. Some viruses cut eIF4G in such a way that the eIF4E binding site is removed and the virus is able to translate its proteins without eIF4E. Also some cellular proteins, the most notable being heat shock proteins, do not require eIF4E in order to be translated. Both viruses and cellular proteins achieve this through an internal ribosome entry site in the RNA or through other RNA translation mechanisms such as those going through eIF3d. eIF4E plays roles outside of translation and other cap-binding proteins can engage in cap-dependent translation in an eIF4E-independent manner including factors such as eIF3D, eIF3I, PARN, the nuclear cap-binding complex CBC. Many of these appear to be dependent on both specific features of transcripts as well as cellular context.
EIF4E, also known as eIF4E, is a protein that plays a crucial role in both protein synthesis and RNA metabolism. In the cytoplasm, it initiates and regulates protein synthesis by binding to the 7-methylguanosine (m7G) cap on messenger RNA (mRNA), facilitating ribosome binding and unwinding of mRNA secondary structures. EIF4E also acts as a regulator of translation and stability in the cytoplasm, participating in the CYFIP1-EIF4E-FMR1 complex to mediate translational repression. Furthermore, EIF4E is involved in mRNA nucleocytoplasmic transport, specifically promoting the export of a subset of mRNAs from the nucleus to the cytoplasm. This export is facilitated by EIF4E's ability to bind to the m7G cap and by the presence of the 50-nucleotide EIF4E sensitivity element (4ESE) in the 3' untranslated region (UTR) of sensitive transcripts. EIF4E's role in mRNA export enhances processes such as RNA capping, processing, and splicing, as well as contributing to the regulation of cell cycle progression, neurogenesis, and spermatogenesis.
EIF4E is also known as AUTS19, CBP, EIF4E1, EIF4EL1, EIF4F, eIF-4E.
