EIF3D
Description
The EIF3D (eukaryotic translation initiation factor 3 subunit D) is a protein-coding gene located on chromosome 22.
EIF3D, encoded by the EIF3D gene in humans, is a subunit of the eukaryotic translation initiation factor 3 (eIF3) complex, which is essential for protein synthesis initiation. eIF3 is a multiprotein complex composed of at least 10 nonidentical subunits. The complex binds to the 40S ribosome and helps maintain the 40S and 60S ribosomal subunits in a dissociated state. It also contributes to the formation of the 40S initiation complex by interacting with the ternary complex of eIF2/GTP/methionyl-tRNA and promoting mRNA binding. EIF3D specifically functions as the major RNA binding subunit of the eIF3 complex. EIF3D interacts with proteins like PHLDA1, EIF3A, and c-Jun mRNA through a non-canonical mechanism. Unlike the typical cap-binding protein EIF4G, EIF3D acts as a cap binding protein for certain mRNAs, such as c-Jun, which have structures in their 5' UTR that inhibit EIF4G binding and promote EIF3D binding. This cap binding activity of EIF3D is crucial for regulating gene expression under cellular stress, such as during glucose deprivation, where EIF3D's binding activity to c-Jun mRNA increases significantly.
EIF3D is a key component of the eukaryotic translation initiation factor 3 (eIF-3) complex, essential for several steps in the initiation of protein synthesis. eIF-3 binds to the 40S ribosome and recruits other initiation factors to form the 43S pre-initiation complex. It stimulates mRNA recruitment to this complex and facilitates the scanning process for the AUG start codon. Additionally, eIF-3 plays a role in ribosomal complex recycling after translation termination, preventing premature subunit joining. This complex targets specific mRNAs involved in cell proliferation, including cell cycle control, differentiation, and apoptosis, using various RNA stem-loop binding mechanisms to regulate translation. EIF3D, specifically, acts as the cap-binding component within the eIF-3 complex, recognizing and binding the 7-methylguanosine cap of a subset of mRNAs.
EIF3D is also known as EIF3S7, eIF3-p66, eIF3-zeta.
