Novel peptide sequence ("IQ-tag") with high affinity for NIR fluorochromes allows protein and cell specific labeling for in vivo imaging

PLoS One. 2007 Jul 25;2(7):e665. doi: 10.1371/journal.pone.0000665.


Background: Probes that allow site-specific protein labeling have become critical tools for visualizing biological processes.

Methods: Here we used phage display to identify a novel peptide sequence with nanomolar affinity for near infrared (NIR) (benz)indolium fluorochromes. The developed peptide sequence ("IQ-tag") allows detection of NIR dyes in a wide range of assays including ELISA, flow cytometry, high throughput screens, microscopy, and optical in vivo imaging.

Significance: The described method is expected to have broad utility in numerous applications, namely site-specific protein imaging, target identification, cell tracking, and drug development.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Bacteriophages / chemistry
  • Coloring Agents
  • Enzyme-Linked Immunosorbent Assay / methods
  • Flow Cytometry / methods
  • Fluorescent Dyes
  • Microscopy, Fluorescence / methods
  • Molecular Sequence Data
  • Peptides / chemistry*
  • Protein Conformation
  • Spectrophotometry, Infrared / methods


  • Coloring Agents
  • Fluorescent Dyes
  • Peptides