Practice question
Question
Which ribosomal site first binds initiator tRNA?
Explanation
Initiator methionyl-tRNA occupies P site first, not A site, during translation initiation. In bacteria, IF2 GTP delivers fMet-tRNAfMet directly to P site base-pairing with AUG positioned by Shine-Dalgarno interaction. In eukaryotes eIF2 GTP delivers Met-tRNAi to 40S P site within 43S complex. This positioning sets reading frame, allowing second aminoacyl-tRNA entry into A site for first peptide bond. P site initiation distinguishes from elongation where tRNAs enter A site, ensuring directionality, start site selection and preventing out-of-frame translation initiation events.
Related blogs
Guides and insights connected to this topic
SARS-CoV-2 Coronavirus: Structure, Genome, Proteins, Replication, Pathogenesis, and Host Interaction
Coronavirus Overview Coronaviruses (CoVs) are enveloped viruses (surrounded by a lipid membrane derived from host cells), belonging to the s...
Coronavirus Structure, Genome, Replication, Symptoms, Pathogenesis, and Prevention
Structure of Coronavirus Coronaviruses (enveloped RNA viruses) fall in the virus family Coronaviridae, order Nidovirales. They are enveloped...
Cucumber Mosaic Virus (CMV): Structure, Genome, Symptoms, Disease Cycle and Management
Cucumber Mosaic Virus (CMV): Introduction and Importance Cucumber Mosaic Virus (CMV) (plant-infecting RNA virus) is one of the most economic...