mScarlet3: a brilliant and fast-maturing red fluorescent protein

Nat Methods. 2023 Apr;20(4):541-545. doi: 10.1038/s41592-023-01809-y. Epub 2023 Mar 27.


We report the evolution of mScarlet3, a cysteine-free monomeric red fluorescent protein with fast and complete maturation, as well as record brightness, quantum yield (75%) and fluorescence lifetime (4.0 ns). The mScarlet3 crystal structure reveals a barrel rigidified at one of its heads by a large hydrophobic patch of internal residues. mScarlet3 behaves well as a fusion tag, displays no apparent cytotoxicity and it surpasses existing red fluorescent proteins as a Förster resonance energy transfer acceptor and as a reporter in transient expression systems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Fluorescence Resonance Energy Transfer*
  • HeLa Cells
  • Humans
  • Luminescent Proteins / metabolism
  • Red Fluorescent Protein


  • Luminescent Proteins