Component of the protein complex eIF4F, which is involved in the recognition of the mRNA cap, ATP-dependent unwinding of 5'-terminal secondary structure and recruitment of mRNA to the ribosome. As a member of the eIF4F complex, required for endoplasmic reticulum stress-induced ATF4 mRNA translation (PubMed:29062139). eIF4F is a multi-subunit complex, the composition of which varies with external and internal environmental conditions. It is composed of at least EIF4A, EIF4E (cap-binding) and EIF4G1/EIF4G3. Interacts with eIF3, mutually exclusive with EIF4A1 or EIFA2, EIF4E and through its N-terminus with PAPBC1. Interacts through its C-terminus with the serine/threonine kinases MKNK1, and with MKNK2. Appears to act as a scaffold protein, holding these enzymes in place to phosphorylate EIF4E. Non-phosphorylated EIF4EBP1 competes with EIF4G1/EIF4G3 to interact with EIF4E; insulin stimulated MAP-kinase (MAPK1 and MAPK3) phosphorylation of EIF4EBP1 causes dissociation of the complex allowing EIF4G1/EIF4G3 to bind and consequent initiation of translation. EIF4G1/EIF4G3 interacts with PABPC1 to bring about circularization of the mRNA. Rapamycin can attenuate insulin stimulation mediated by FKBPs. Interacts with EIF4E3. Interacts with CIRBP and MIF4GD. Interacts with RBM4. Interacts with HNRNPD/AUF1; the interaction requires RNA. Directly interacts with EIF4G1 in an RNA-independent manner (PubMed:22872150). (Microbial infection) Interacts with rotavirus A NSP3; in this interaction, NSP3 takes the place of PABPC1 thereby inducing shutoff of host protein synthesis. (Microbial infection) Interacts with human adenovirus 5 protein 100K; this interaction promotes translational shunt in presence of polysomes containing viral tripartite leader mRNAs. Phosphorylated at multiple sites in vivo. Phosphorylation at Ser-1185 by PRKCA induces binding to MKNK1. Following infection by certain enteroviruses, rhinoviruses and aphthoviruses, EIF4G1 is cleaved by the viral protease 2A, or the leader protease in the case of aphthoviruses. This shuts down the capped cellular mRNA transcription. The disease is caused by variants affecting the gene represented in this entry. Produced by alternative initiation at Met-41 of isoform A. Produced by alternative initiation at Met-88 of isoform A. Produced by alternative initiation at Met-165 of isoform A. Produced by alternative initiation at Met-197 of isoform A. Produced by alternative splicing. Produced by alternative splicing. Produced by alternative splicing. Belongs to the eukaryotic initiation factor 4G family. Truncated N-terminus. Truncated N-terminus. Aberrant splicing.