Channelrhodopsin-2, a Directly Light-Gated Cation-Selective Membrane Channel
Proceedings of the National Academy of Sciences, 2003 · paper · Biomedicine
Shows through expression in frog oocytes and mammalian cells that Channelrhodopsin-2 from the green alga Chlamydomonas is a directly light-gated, cation-selective ion channel. It also characterizes its desensitization and demonstrates that illumination can depolarize cells.
Checked: PDF from europepmc.org, fetched 4 Oct 2026. Page numbers are those of that PDF.
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None that passed a second check.
10 minor (typos and the like; most checked by the judge only)
Reference or label The Fig. 4 legend gives the Chop1 antiserum as 'Chop1310–546' and 'Chop1–310-546 fragment', but the Fig. 4b panel label reads 'antibody: ChR1_310-547'.
- p. 5 Fig. 4 legend (b and c)
raised against a Chop1–310-546 fragment in rabbits
- p. 5 Fig. 4b blot label
antibody: ChR1_310-547
- p. 5 Fig. 4 legend
Chop1310–546 antiserum (1:1,000 dilution)
Only the authors can say what is right here.
Judge's note: The legend crop (p.5) shows 310–546 twice. The panel label in the full p.5 image reads 'ChR1_310-547'. The Chop2 antibody (617–723) is labelled the same way in the legend and on the panel. The end residue differs by one; only the authors can say which is correct.
Second check: another model agreed
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Wording The text says 'even for tetra-methyl-ammonium (Fig. 1f)' is permeable, but Fig. 1f gives only 'TMA+ ≤ 0.06' (an upper bound), and tetra-ethyl-ammonium does not appear in Fig. 1f.
- p. 2 Results, last paragraph
di-methyl-ammonium, and even for tetra-methyl-ammonium
- p. 2 Fig. 1f table
TMA+ ≤ 0.06
- p. 2 Results text, last paragraph
and even for tetra-methyl-ammonium (Fig. 1f), whereas tetra-ethyl-ammonium does not measurably permeate ChR2
- p. 5 Discussion, paragraph 3
must be wide (≈6 Å in diameter) to be permeable to methylated ammonium cations
Only the authors can say what is right here.
Judge's note: In the Fig. 1f table on p.2, TMA+ is given only as '≤ 0.06'; every other ion has a value ± error. The Results text presents TMA permeation as a positive finding, and the Discussion (p.5) uses methylated-ammonium permeability to infer a pore of about 6 Å. The authors should clarify whether ≤0.06 is a detection limit or a measured value.
Second check: another model agreed
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Typo 'photocur-rrent' (Introduction, p.1, right column) should read 'photocurrent'.
- p. 1 Introduction, right column, line 4
photocur-rrent is <50 µs
Judge's note: The page 1 image shows 'photocur-' at the end of one line and 'rrent' at the start of the next, so the word is printed with a triple r.
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Typo 'heterologous expression of ChR2 had not re-ported' is missing 'been' ('had not been reported').
- p. 2 Introduction, final paragraph (left column bottom)
heterologous expression of ChR2 had not re-ported
- p. 2 end of Introduction
heterologous expression of ChR2 had not re-
Judge's note: The page 2 image, bottom of the left column, reads 'Up to now, heterologous expression of ChR2 had not re-ported'.
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Typo Fig. 1 legend (f): 'Permability ratios' should read 'Permeability ratios'.
- p. 2 Fig. 1 legend (f)
Permability ratios for different mono-valent cations
- p. 2 Fig. 1 legend (f)
Permability ratios
- p. 2 Fig. 1 legend (f)
Goldmann–Hodgkin–Katz
- p. 2 Fig. 1 legend (f)
Permability ratios for different mono-
Judge's note: The crop of the Fig. 1 legend on p.2 shows '(f) Permability ratios for different mono-valent cations'. The Goldmann spelling is handled in C007.
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Typo Fig. 1 legend (f): 'Goldmann–Hodgkin–Katz equation' should read 'Goldman–Hodgkin–Katz'.
- p. 2 Fig. 1 legend (f)
Goldmann–Hodgkin–Katz equation
Judge's note: The crop shows 'Goldmann–Hodgkin–Katz equation (31)'. The standard eponym is Goldman, with one n.
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Typo Fig. 1 legend (f): '115 mM XCl, 2 mM BaCl2, 1 MgCl2, pH 9' is missing the unit for MgCl2 (should be '1 mM MgCl2').
- p. 2 Fig. 1 legend (f)
2 mM BaCl2, 1 MgCl2, pH 9
Judge's note: The crop of the p.2 legend shows '1 MgCl2' with no mM, while every neighbouring concentration has mM.
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Typo Fig. 1 legend (f): 'assuming cytoplasmic ≈100 K+' gives no concentration unit (presumably mM).
- p. 2 Fig. 1 legend (f)
assuming cytoplasmic ~100 K+
Judge's note: The crop shows 'assuming cytoplasmic ≈100 K+ and a pHi of 7.3', with no unit.
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Typo Ref. 5 'Hardie, R. C. & Raghu, P. (2001) Nature 186–193.' has no volume number.
- p. 6 Reference 5
Hardie, R. C. & Raghu, P. (2001) Nature 186–193.
Judge's note: The crop of the p.6 reference list shows no bold volume number, whereas the other journal entries all have one. The correct volume (413) rests on outside knowledge.
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Typo Ref. 11 author list contains 'Büldt, G., T., S., Scheidig, A. J.': one author is given as initials with no surname.
- p. 6 Reference 11
Büldt, G., T., S., Scheidig, A. J.
- p. 6 Reference list, ref. 11
Bu¨ldt, G., T., S., Scheidig, A. J.
Judge's note: The crop of ref. 11 on p.6 shows 'T., S.' between Büldt and Scheidig, so the garbling is in print. The missing surname (likely Savopol) rests on outside knowledge.
Second check: none (judge only)