Case No. 119 · the exotic forty · have you seen this molecule?

Telomeric G-quadruplex

your chromosome ends, folded in fours

File sealed

The detectives are still writing this one up. The poster and the facts are below; the film and the interrogation room open soon.

Booking photographs

Telomeric G-quadruplex, front view, against a height chart in nanometers — FRONT

Telomeric G-quadruplex, side view — SIDE · PDB 1KF1

The suspect, from its real atomic coordinates. Drag to turn it. Height chart in nanometers, a line every 0.2 nm. Unwound, your longest chromosome is about nineteen million times longer.

Rap sheet

Answers to: G4. Spells TTAGGG.
Height: 4.4 nm, on its edge.
Weight: 12 zeptograms
Build: Three stacked G-quartets, potassium in the core.
Topology: All four strands run one way. Propeller loops.
Habits: Five-plus known folds. This one in crystals and crowds.
Associates: All 91 vertebrates checked, fish to mammals: chromosomes end in TTAGGG.
Lifespan: In blood, newborns’ run a fifth longer than their parents’.
Last seen: In a crystal grown in potassium, in a lab in London.

100,000

TTAGGGs capping the chromosomes in one white blood cell, give or take.
Four make one of these. You’ve never seen one.

CASE FILE: Parkinson, G.N. et al. (2002) Crystal structure of parallel quadruplexes from human telomeric DNA. Nature 417, 876–880.

The poster on the street

The wanted poster for Telomeric G-quadruplex

This is the photocopied wanted poster for Telomeric G-quadruplex, No. 119 of the exotic forty. They were made for noticeboards around Boston, Cambridge and the rest of the east coast.

Found one? Scan its QR code with your phone. If you're a signed-in player, the sighting goes on your record with +1 XP.

Not a player yet? Join the Epic Quest: the real role-playing game of Molecular Reality, a nanopore lab, with the CEO as gamemaster.