eukaryotic initiation factor 3; ribosome dissociation factor (eIF3)

Function

• the eIF-3 complex associates with the 40S ribosome & facilitates recruitment of eIF-1, eIF-1A, eIF-2:GTP:methionyl-tRNAi & eIF-5 to form the 43S preinitiation complex (43S PIC)
• the eIF-3 complex stimulates mRNA recruitment to the 43S PIC & scanning of the mRNA for AUG recognitio
• the eIF-3 complex is also required for disassembly & recycling of posttermination ribosomal complexes & subsequently prevents premature joining of the 40S ribosomal subunit & 60S ribosomal subunit prior to initiation
• the eIF-3 complex interacts with RPS6KB1 under conditions of nutrient depletion
• mitogenic stimulation leads to binding & activation of a complex composed of MTOR & RPTOR, leading to phosphorylation & release of RPS6KB1 & binding of EIF4B to eIF-3

Structure

• composed of 13 subunits:
  • EIF3A, EIF3B, EIF3C, EIF3D, EIF3E, EIF3F, EIF3G, EIF3H, EIF3I, EIF3J, EIF3K, EIF3L & EIF3M
• the eIF-3 complex appears to include 3 stable modules:
  • module A is composed of EIF3A, EIF3B, EIF3G & EIF3I
  • module B is composed of EIF3F, EIF3H, & EIF3M
  • module C is composed of EIF3C, EIF3D, EIF3E, EIF3K & EIF3L
• EIF3C of module C binds EIF3B of module A & EIF3H of module B, thereby linking the 3 modules

More general terms

• initiation factor
• multisubunit protein

Additional terms

• protein synthesis initiation

Components

• eukaryotic translation initiation factor 3 subunit C-like protein (EIF3CL)