[1] The complementary sequence (CCUCCU), called the anti-Shine-Dalgarno (ASD) is contained in the 3’ end of the 16S region of the smaller (30S) ribosomal subunit.
[2][3] Variations of the 5'-AGGAGG-3' sequence have been found in Archaea as highly conserved 5′-GGTG-3′ regions, 5 basepairs upstream of the start site.
Additionally, some bacterial initiation regions, such as rpsA in E.coli completely lack identifiable SD sequences.
[5] The level of complementarity of the mRNA SD sequence to the ribosomal ASD greatly affects the efficiency of translation initiation.
[6] This only holds up to a certain point - having too rich of a complementarity is known to paradoxically decrease the rate of translation as the ribosome then happens to be bound too tightly to proceed downstream.
[6] The composition of nucleotides in the spacer region itself was also found to affect the rate of translation initiation in one study.
At a higher-than-usual temperature (~42 °C), the RBS secondary structure of heat shock proteins becomes undone thus allowing ribosomes to bind and initiate translation.
[8] Translation initiation happens following recruitment of the ribosome, at the start codon (underlined) found within the Kozak consensus sequence ACCAUGG.