Fluorescence Recovery After Photobleaching


Prescreen for LCP Crystal Growth

Determine Protein Mobility

High protein mobility and fast diffusion rates correlate well with crystallization conditions.


Save Time + Money

Rule Out Sub-Optimal Conditions

Focus your research on those conditions conducive to LCP crystal growth. 


Convenient + Easy-to-Use

Fully Automated Analysis

Initiate a complete analysis of your plate with a few clicks and store all your data in one spot.

Prescreen Crystallization Conditions

One of the main factors for successful LCP crystallization is the ability of the protein to diffuse within the lipid bilayer. The diffusion rate of the protein is influenced by protein aggregation, structural properties of the LCP, and the chemical environment.

The diffusion rate can be determined by FRAP, which measures the amount of time required for the fluorescence intensity of a tagged protein to reestablish itself within a small area in the LCP drop that has been subject to optical bleaching.


Using FRAP, you can screen your crystallization experiment in under 50 minutes to determine the mobile fraction of your protein and whether or not that condition is conducive to forming protein crystals.

Data Collection Options

High Throughput
Each complete LCP-FRAP process takes about 15-20 minutes. To increase throughput, the system can be set to collect only the end state fluorescence intensity.


Only mobile fraction results are measured in this high throughput mode, which provides researchers the information needed to identify positive conditions. Most often, a mobile fraction >0.20 (20%) is a good threshold for a positive condition. In this mode, you can collect mobile fraction data on an entire 96-well plate in under 50 minutes.

Complete Recovery
Drops imaged using the complete recovery setting will be photographed many more times following the bleach time (time zero) in order to more closely capture molecular diffusion and generate a single- or double-component Bessel function curve.


Single-component recovery curves are enough for most experiments to analyze a protein´s diffusion rate and recovery time. However, if the experiment has two different types of molecules diffusing, such as labeled lipids, then a double-component Bessel function curve is more appropriate.

Fast and Easy Data Review

FRAP automatically calculates the percent mobile fraction for each drop. The mobile fraction score can then be related to the ability of the protein in that condition to form protein crystals. The higher the mobility, the greater the chance for crystallization. Scores are displayed in a color-coded overview allowing users to identify positive wells at a glance.

Models to Fit Your Workflow and Budget

FRAP comes in two configurations to better fit your lab's needs:


A benchtop model capable of imaging two plates at a time. Best for lab's where throughput is not a concern.


An integrated model that is built into a ROCK IMAGER 1000 which allows you to store and automatically image up to 970 plates. Two plates can be imaged at the same time - one with visible light and one with FRAP.

FRAP imaging models

FRAP - Benchtop: Overview




Methods used to study the oligomeric structure of G-protein-coupled receptors

Guo H, An S, Ward R, et al. Methods used to study the oligomeric structure of G-protein-coupled receptors. Bioscience Reports. 2017;37(2):BSR20160547. doi:10.1042/BSR20160547.
Salom D, Padayatti PS, Palczewski K. Crystallization of G Protein-Coupled Receptors. Methods in cell biology. 2013;117:451-468. doi:10.1016/B978-0-12-408143-7.00024-4.
Gustavo Fenalti, Enrique E. Abola, Chong Wang, Beili Wu, Vadim Cherezov, Chapter Twenty - Fluorescence Recovery After Photobleaching in Lipidic Cubic Phase (LCP-FRAP): A Precrystallization Assay for Membrane Proteins, Editor(s): Arun K. Shukla, In Methods in Enzymology, Academic Press, Volume 557, 2015, Pages 417-437, ISSN 0076-6879, ISBN 9780128021835,
Milić D, Veprintsev DB. Large-scale production and protein engineering of G protein-coupled receptors for structural studies. Frontiers in Pharmacology. 2015;6:66. doi:10.3389/fphar.2015.00066.
Xin Yin, Henghao Xu, Michael Hanson and Wei Liu, GPCR Crystallization Using Lipidic Cubic Phase Technique, Current Pharmaceutical Biotechnology, volume 15, issue 10, pages 971-979, year 2014, issn 1389-2010/1873-4316, doi 10.2174/1389201015666140922110325
Siu FY, He M, de Graaf C, et al. Structure of the class B human glucagon G protein coupled receptor. Nature. 2013;499(7459):10.1038/nature12393. doi:10.1038/nature12393.
Stevens RC, Cherezov V, Katritch V, et al. GPCR Network: a large-scale collaboration on GPCR structure and function. Nature reviews Drug discovery. 2013;12(1):25-34. doi:10.1038/nrd3859.
Fei Xu, Wei Liu, Michael A. Hanson, Raymond C. Stevens, and Vadim Cherezov
Crystal Growth & Design 2011 11 (4), 1193-1201

DOI: 10.1021/cg101385e

Joseph JS, Liu W, Kunken J, Weiss TM, Tsuruta H, Cherezov V. Characterization of Lipid Matrices for Membrane Protein Crystallization by High-Throughput Small Angle X-ray Scattering. Methods (San Diego, Calif). 2011;55(4):342-349. doi:10.1016/j.ymeth.2011.08.013.
Cherezov V. Lipidic Cubic Phase Technologies for Membrane Protein Structural Studies. Current opinion in structural biology. 2011;21(4):559-566. doi:10.1016/
Vadim Cherezov, Jeffrey Liu, Mark Griffith, Michael A. Hanson, and Raymond C. Stevens
Crystal Growth & Design 2008 8 (12), 4307-4315

DOI: 10.1021/cg800778j

Computer Requirements

The standard FRAP controlling computer offered with the instrument supports imaging with continuous multiple focus level imaging (z-slicing) and processing of all images.

FRAP uses the ROCK IMAGER control software which operates with 64-bit Windows 10 or 64/32 bit Windows 7.

Electrical Specifications

Instrument: 100-240 VAC, 50-60 Hz, 600 W max, 1 PH

Computer: 100-240 VAC, 50-60 Hz, 525 W max, 1 PH

Temperature Regulation

System can operate in any temperature from 4° C to 30° C

Internal temperature can be controlled to within 5° C below and 7° C above ambient

Compatible Plates

SBS standard LCP plates (127.8 mm x 85.5 mm x 14.4 mm)

LCP thin glass plates (127.8 mm x 85.5 mm x 1 mm)

Physical Dimensions - FRAP Benchtop

Width: 641 mm (26")

Depth: 696 mm (28")

Height: 837 mm (35")

Weight: 70 kg (155 lbs)

Physical Dimensions - FRAP Integrated with RI1000

Width: 834 mm (33")

Depth: 1230 mm (49")

Height: 2197 mm (87")

Weight: 462 kg (1019 lbs)