initiation proteins involved in eukaryotic translation

eIF4F

• composed of: eIF4E, eIF4A, eIF4G

• composed of: eIF3, eIF5, eIF6

• composed of: eIF1, eIF2, eIF4B

• composed of: eIF4E, eIF4B, eIF4G

eIF2

• primarily responsible for bringing the initiator Met-tRNA to the 40s subunit of the ribosome

• involved in the elongation phase of protein synthesis

• functions as a chaperone for protein folding

• acts as a signal for protein degradation

Kozak sequence

• A sequence that surrounds the start sequence for translation in eukaryotes. The 40s subunit scans along the mRNA until it reaches this sequence

• A type of RNA that is involved in the synthesis of proteins

• A sequence that signals the termination of translation in prokaryotes

• A region of DNA that regulates gene expression

Poly-A binding protein (PABP)

• binds to the 3' end of the poly A tail and interacts with eIF4G which circularizes the mRNA, therefore enhancing translational efficiency

• binds to the 5' end of the mRNA and prevents degradation

• interacts with ribosomes to initiate translation

• is involved in the splicing of introns from pre-mRNA

eIF4E

• the cap binding protein and is also a part of the eIF4F complex

• a type of RNA polymerase

• a ribosomal protein involved in translation

• a transcription factor that regulates gene expression

43S pre-initiation complex

• eIF1, eIF1A, eIF2-GTP, eIF3

• eIF4E, eIF4G, eIF4A, eIF5

• eIF2, eIF5B, eIF3, eIF6

• eIF1, eIF2, eIF3, eIF4B

eIF4A

• a helices utilized in initiation (and also a part of the eIF4F complex)

• a type of RNA polymerase

• a protein involved in DNA replication

• a component of the ribosome

eIF4G

• Helps link the cap to the 43s pre-initiation complex by bringing the 5' and 3' ends together, circularizing the mRNA and is part of the eIF4F complex

• Inhibits the translation process by preventing ribosome assembly

• Acts as a chaperone for mRNA degradation

• Facilitates the binding of tRNA to the ribosome during elongation

eIF1A

• helps separate the large subunit from the small subunit of the ribosome; it binds into the A site

• is involved in the initiation of transcription in eukaryotes

• functions as a chaperone for protein folding

• is a component of the spliceosome

Internal ribosome entry site (IRES)

• allows for translation initiation without the 5' cap in certain eukaryotes

• is a sequence that promotes ribosome binding at the 5' end

• is involved in the degradation of mRNA

• is a mechanism for protein folding