Skip to main content
. Author manuscript; available in PMC: 2008 Jun 1.
Published in final edited form as: J Mol Biol. 2007 Mar 20;369(2):512–524. doi: 10.1016/j.jmb.2007.03.032

Figure 3.

Figure 3

FRET-based analysis of SRP assembly. (A) Scheme for monitoring SRP assembly using Alexa 488-derivatized SRP19 (green) and the Alexa 555-LS RNA (yellow and gray). SRP54 (purple) binding is detected by its affect on the SRP19-RNA complex. (B, C) Three distinct assembly steps are detected during native SRP19-SRP54-SRP RNA ternary complex formation. (1) A rapid burst phase quenching of fluorescence during initial SRP19-RNA assembly (green). (2) Well-resolved increase or decrease in fluorescence emission intensity as the SRP19-RNA complex matures to the native structure (green). (3) An increase in fluorescence intensity due to SRP54 binding to the pre-formed SRP19-RNA complex (purple). Free Alexa 647 reference fluorophore is gray.