Alternative Splicing — Molecular Biology in 60 Seconds #Shorts

Summary

Alternative splicing allows one gene to produce multiple related proteins from the same pre-mRNA transcript.

A pre-mRNA contains exons, which code for protein, and introns, which lie between them. The spliceosome—a complex involving five small ribonucleoproteins (U1, U2, U4, U5, and U6)—recognizes splice sites around introns. Each intron is looped into a lariat and removed, and the neighboring exons are joined.

When all exons are retained, the result is the canonical mature mRNA, called isoform A in the example. The spliceosome can also skip a cassette exon: omitting exon 3 creates a second mature mRNA, isoform B.

Different mRNA isoforms can produce proteins with different functions, locations, or interaction partners. In some cases, their roles may even oppose one another. The subtitles state that roughly 95% of human genes are alternatively spliced, allowing about 20,000 genes to generate a much larger range of protein variants.

Speaker and source

• Narrator: Unidentified voiceover explaining alternative splicing.