Erratum:

The following corrections should be noted for the Protocol by Zheng and Zagotta. The pages indicated are from the PDF:

• Page 7: To the last sentence of the first paragraph, the word "or" should be added to this phrase "...to other signals [or] using other types of image acquisition software."
• Page 7: To instruction number 2, the phrase "fine focus" should read "fine adjustments".
• Page 7: In the note to instruction number 3, The phrase "...that there is no background present." should be deleted.
• Page 7: In the note to instruction number 5, the phrase "...by the patch amplifier..." should read "...by the pulse acquisition software...".
• Page 8: The sentence "Additional approaches to reducing background are discussed in Notes and Remarks." Should read "Additional approaches to reducing background are discussed in Nonspecific Fluorescence Signals."
• Page 11: In the definition of the terms for Equation 2 of Fig. 7, the word "subtracted" should be deleted both times it appears.
• Page 11: In the last sentence of the first paragraph, the abbreviation "(FR)" should appear immediately following "FRET Ratio".

The online display of the figure and the full text view of the article have been corrected. A corrected PDF is available starting May 27, 2003.

A PDF of the originally published with the incorrect figure and original text is also available. http://stke.sciencemag.org/cgi/data/sigtrans;2003/176/pl7/DC1/1