Initiation complex

Definition

The initiation complex is a multi-component assembly formed during the early stage of translation in protein synthesis. It consists of mRNA, the ribosomal subunits, initiator tRNA, and various initiation factors.

5 Must Know Facts For Your Next Test

1. The initiation complex is essential for accurate translation initiation in both prokaryotes and eukaryotes.
2. In eukaryotes, the small ribosomal subunit binds to the 5' cap of mRNA to start forming the initiation complex.
3. Initiation factors such as eIFs (eukaryotic initiation factors) are crucial for assembling the initiation complex in eukaryotic cells.
4. The initiator tRNA carrying methionine (Met-tRNAi) binds to the start codon AUG within the initiation complex.
5. Formation of the complete initiation complex results in the joining of large and small ribosomal subunits, allowing elongation to commence.

Review Questions

• What components are required to form the initiation complex during translation?
• How does the role of initiation factors differ between prokaryotes and eukaryotes?
• Why is the formation of an accurate initiation complex critical for protein synthesis?

Related terms

Ribosome: A molecular machine composed of rRNA and proteins that synthesizes polypeptides by translating mRNA.

mRNA:

Messenger RNA that carries genetic information from DNA to the ribosome for protein synthesis.

Initiation Factors: Proteins that assist in forming the initiation complex by facilitating binding between mRNA, tRNA, and ribosomes.