ledersekvens

Ledersekvens, often translated as "leader sequence" or "leading sequence," refers to a specific region of messenger RNA (mRNA) that precedes the start codon and is crucial for the initiation of protein translation. This sequence, typically found in prokaryotes, plays a vital role in recruiting the ribosome to the correct starting point on the mRNA molecule.

In bacteria, the most well-known leader sequence element is the Shine-Dalgarno sequence. This purine-rich sequence, usually AGGAGG, binds to a complementary pyrimidine-rich sequence located on the 16S ribosomal RNA (rRNA) component of the small ribosomal subunit. This interaction anchors the ribosome to the mRNA, facilitating the accurate positioning of the start codon (usually AUG) for translation to begin.

The length and specific sequence of leader regions can vary between different genes and organisms. While prominent in prokaryotes, eukaryotes generally have a different mechanism for translation initiation involving a 5' cap structure and scanning by the ribosome. However, some eukaryotic viruses can utilize leader sequences to influence their translation efficiency. The study of leader sequences is fundamental to understanding gene expression regulation at the translational level.