The molecule and where it comes from
MOTS-c is a short, simple peptide: a single chain of 16 amino acids with no disulfide bonds and no complex fold. What m…
Sixteen residues read out of a ribosomal RNA gene
MOTS-c is a short, simple peptide: a single chain of 16 amino acids with no disulfide bonds and no complex fold. What makes it remarkable is not its shape but its address. It is encoded by a small open reading frame nested inside the mitochondrial 12S rRNA gene (MT-RNR1), a region that classical genetics said only made ribosomal RNA.
This unit reads the molecule and its genomic origin together: the sequence and the one residue (position 14) that carries a famous polymorphism, how a peptide can be hidden inside an rRNA gene, and why the mitochondrial genetic code matters. The chemistry here is settled fact, which makes it a clean place to practice separating what is known from what is merely claimed.
Key terms
The 16-residue chain
MOTS-c is one short chain of 16 amino acids. There is no disulfide bridge, no copper, no sugar, just a small peptide. The one feature worth memorizing is position 14: a lysine here can be swapped for glutamine by a single mtDNA change (the K14Q variant), and that one-residue difference is the hook for the human-genetics story told later. Tap the regions to explore the chain.
Because the chain is short and unstructured, MOTS-c behaves like a flexible signaling fragment rather than a folded enzyme. That simplicity is part of why its exact molecular target has been hard to pin down: it does the work through metabolic and gene-regulatory effects rather than by slotting into one obvious receptor.