initiation codon

noun

ini·​ti·​a·​tion codon in-ˌish-ē-ˈā-shən- 

variants also initiator codon

: start codon

Efficient initiation of translation depends upon the existence of a group of six to eight purine-rich nucleotides just upstream from the AUG initiation codon.

—James D. Watson et al., Recombinant DNA: A Short Course