mRNA attaches itself to smaller subunit of ribosome with its cap coming in contact with 3’ end of 18 S rRNA. AUG or GUG comes to lie over P-site to produce 40S-mRNA complex.P-site now attracts met tRNA. The anticodon of tRNA comes to lie opposite to initiation codon. It gives rise to form 40S-mRNA-tRNAmet.The larger subunit of ribosome now attaches to 40S-mRNA-tRNAmet complex to form 80S mRNA-tRNA complex. Mg2+ is essential for union of the two subunits of ribosomes. A site becomes operational. Second codon of mRNA lies over it.