In vivo expression of a light-activatable potassium channel using unnatural amino acids

Neuron. 2013 Oct 16;80(2):358-70. doi: 10.1016/j.neuron.2013.08.016.


Optical control of protein function provides excellent spatial-temporal resolution for studying proteins in situ. Although light-sensitive exogenous proteins and ligands have been used to manipulate neuronal activity, a method for optical control of neuronal proteins using unnatural amino acids (Uaa) in vivo is lacking. Here, we describe the genetic incorporation of a photoreactive Uaa into the pore of an inwardly rectifying potassium channel Kir2.1. The Uaa occluded the pore, rendering the channel nonconducting, and, on brief light illumination, was released to permit outward K(+) current. Expression of this photoinducible inwardly rectifying potassium (PIRK) channel in rat hippocampal neurons created a light-activatable PIRK switch for suppressing neuronal firing. We also expanded the genetic code of mammals to express PIRK channels in embryonic mouse neocortex in vivo and demonstrated a light-activated PIRK current in cortical neurons. These principles could be generally expanded to other proteins expressed in the brain to enable optical regulation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cerebral Cortex / metabolism
  • Excitatory Amino Acid Agonists / chemical synthesis
  • Excitatory Amino Acid Agonists / pharmacology*
  • Gene Expression / physiology*
  • HEK293 Cells
  • Hippocampus / physiology
  • Humans
  • Light*
  • Membrane Potentials / physiology
  • Mice
  • Neural Inhibition / physiology
  • Neurons / physiology
  • Potassium Channels, Inwardly Rectifying / biosynthesis*
  • Potassium Channels, Inwardly Rectifying / genetics*
  • Potassium Channels, Inwardly Rectifying / physiology


  • Excitatory Amino Acid Agonists
  • Kir2.1 channel
  • Potassium Channels, Inwardly Rectifying