Document Detail

Counting single photoactivatable fluorescent molecules by photoactivated localization microscopy (PALM).
MedLine Citation:
PMID:  23045631     Owner:  NLM     Status:  MEDLINE    
We present a single molecule method for counting proteins within a diffraction-limited area when using photoactivated localization microscopy. The intrinsic blinking of photoactivatable fluorescent proteins mEos2 and Dendra2 leads to an overcounting error, which constitutes a major obstacle for their use as molecular counting tags. Here, we introduce a kinetic model to describe blinking and show that Dendra2 photobleaches three times faster and blinks seven times less than mEos2, making Dendra2 a better photoactivated localization microscopy tag than mEos2 for molecular counting. The simultaneous activation of multiple molecules is another source of error, but it leads to molecular undercounting instead. We propose a photoactivation scheme that maximally separates the activation of different molecules, thus helping to overcome undercounting. We also present a method that quantifies the total counting error and minimizes it by balancing over- and undercounting. This unique method establishes that Dendra2 is better for counting purposes than mEos2, allowing us to count in vitro up to 200 molecules in a diffraction-limited spot with a bias smaller than 2% and an uncertainty less than 6% within 10 min. Finally, we demonstrate that this counting method can be applied to protein quantification in vivo by counting the bacterial flagellar motor protein FliM fused to Dendra2.
Sang-Hyuk Lee; Jae Yen Shin; Antony Lee; Carlos Bustamante
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2012-10-08
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  109     ISSN:  1091-6490     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-24     Completed Date:  2013-01-07     Revised Date:  2013-07-11    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  17436-41     Citation Subset:  IM    
Departments of Physics, University of California, Berkeley, CA 94720, USA.
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MeSH Terms
Fluorescent Dyes / chemistry*
Microscopy / methods*
Models, Theoretical
Proteins / analysis*
Grant Support
R01-GM032543/GM/NIGMS NIH HHS; //Howard Hughes Medical Institute
Reg. No./Substance:
0/Fluorescent Dyes; 0/Proteins

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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