Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4
Nature, 1970 · paper · Biomedicine
Isolates and characterizes abnormal head precursors (preheads) of bacteriophage T4 produced by mutations in genes 21, 24 and 23. It reports that the capsid lattice can expand without the maturation cleavages, and that gene 24 vertex completion is needed for cleavage.
Checked: PDF from europepmc.org, fetched 6 Oct 2026. Page numbers are those of that PDF.
3 findings
Substance Text: "Preheads composed of wild-type P23 were 100% solubilized under all conditions tested"; Table 2 gives the 21(tsN8) preheads as 60 at 25°C and 85 at 55°C, reaching 100 only at 65°C.
- p. 7 Results, (ii) 23ts mutant preheads
100% solubilized under all conditions
- p. 7 Table 2, column 21(tsN8), rows 25 and 55 °C
60
- p. 7 Results, (ii) 23ts mutant preheads
were 100% solubilized under all conditions tested
- p. 7 Table 2, 21(tsN8) column
60 ... 85 ... 100
Only the authors can say what is right here.
Judge's note: On the p7 image, the 21(tsN8) column of Table 2 reads 60 (25°C), blank (35 and 45°C), 85 (55°C) and 100 (65°C). The footnote defines the values as percent P23 released relative to 1 h at 65°C. The sentence directly follows the one introducing Table 2, and the 21(tsN8) column is the only wild-type-P23 prehead in the table. No other statement in the paper reconciles the two; the authors may have had other, untabulated conditions in mind.
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Reference or label Fig. 6 legend: "The distribution of classes of particles in uncomplemented 24- crude lysates is given in Table 2"; that distribution is in Table 3 ("Elongated head-related structures in lysates of 24(amN65)"), while Table 2 is "Resistance to solubilization in 1% SDS".
- p. 12 Fig. 6 legend
classes of particles in uncomplemented 24- crude lysates is given in Table 2
- p. 7 Table 2 title
Resistance to solubilization in 1% SDS
- p. 13 Table 3 title
Elongated head-related structures in lysates of 24(amN65)
- p. 12 Fig. 6 legend
is given in Table 2
Judge's note: Checked the legend on the p12 image, Table 2 on p7 and Table 3 on p13. The Results text on p11 itself says "Table 3 lists the distribution of the various types of elongated particles". The pointer should read Table 3.
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Wording Methods: "1% uranyl acetate at a pH of 4.5 was used for negative staining"; Fig. 6 legend: "Staining after adsorptions to the grid was with 1% uranyl acetate (pH 4.2) in all cases."
- p. 2 Methods, Electron microscopy
1% uranyl acetate at a pH of 4.5
- p. 12 Fig. 6 legend
1% uranyl acetate (pH 4.2) in all cases
- p. 12 Fig. 6 legend
1% uranyl acetate (pH
Only the authors can say what is right here.
Judge's note: Both values are legible on the page images (p2 Methods, p12 Fig. 6 legend). Methods describes a single staining condition and nothing in the paper explains a different pH for Fig. 6. Which value is right cannot be told from the paper.
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11 minor (typos and the like; most checked by the judge only)
Wording Discussion says of the 14K and 17K proteins "These must be core components, because they are not present in the core-deficient 23ts preheads", whereas Results say they "decreased in proportion to the P22 and IpIII" in the 23ts mutants and Table 1 gives the 14K protein as 35 (2) in the 21(tsN8)-23(tsA78) 14C column.
- p. 17 Discussion, left column
because they are not present in the core-deficient 23ts preheads
- p. 6 Results, left column
decreased in proportion to the P22 and IpIII
- p. 3 Table 1, 14K row, 21(tsN8)-23(tsA78) 14C column
35 (2)
Only the authors can say what is right here.
Judge's note: Viewed both crops and the page 3 image of Table 1 (printed rotated; it is not in the text layer). In the 21(tsN8)-23(tsA78) 14C column the bottom entries read 44 (2), 100, a blank, 35 (2), 85 (2) against the rows P21, P22, 17K, 14K, 17.5K, so 14K is quantitated at about 35 copies, against 250 (14C) in 21ts preheads. That is reduced, not absent. Results on page 6 also say "The 17K protein seemed to be missing in the 23ts preheads, but a slightly larger protein was present", so "not present" fits 17K only. I found no statement elsewhere that reconciles the Discussion wording with the table. This is an overstatement in wording; the row alignment of the rotated table was read by eye from a small image, hence a query for the authors and not a correction.
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Wording Text: "Figures 1c and d show similar gradients of 24(amN65) particles and 23ts particles"; the Fig. 1 legend has "Panels c and d are SDS gels of gradients of 21(tsN8)-23(tsA78) preheads and 24(amN65) preheads, respectively", so the text lists the samples in the reverse of panel order.
- p. 5 Results, left column
Figures 1c and d show similar gradients of 24(amN65) particles and 23ts par-
- p. 4 Fig. 1 legend
Panels c and d are SDS gels ofgradients of21(tsN8)-23(tsA 78) preheads and 24(amN65) preheads, respectively
- p. 5 Results
Figures lc and d show similar gradients of 24(amN65) particles and 23ts particles
- p. 4 Fig. 1 legend
Panels c and d are SDS gels ofgradients of21(tsN8)-23(tsA 78) preheads and 24(amN65) preheads
Judge's note: Checked the p5 text and p4 legend on the images. The sentence has no "respectively", and the following sentences correctly assign Fig. 1d to the 24- preheads and Fig. 1c to 21(tsN8)-23(tsA78). So this is a misleading ordering, not a false statement.
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Wording Fig. 6 legend describes the tabulated lysates as "uncomplemented 24- crude lysates", but Table 3 footnote a says "The pellets were resuspended into the donor lysate (21-22-23)", which Methods define as the P24 donor lysate.
- p. 12 Fig. 6 legend
uncomplemented 24- crude lysates
- p. 13 Table 3 footnote a
The pellets were resuspended into the donor lysate (21-22-23) 100× concentrated
- p. 13 Table 3 footnote a
The pellets were resuspended into the donor lysate (21-22-23)
Only the authors can say what is right here.
Judge's note: Read the p12 legend and the p13 footnote on the images. Methods on p2 define the 21-22-23 lysate as the P24 donor. By its own footnote, Table 3 (the table the legend evidently means, see C011) was made from cells lysed into donor lysate and fixed within about 5 min. The legend may be loosely contrasting crude lysates with the purified particles in the figure; the paper does not say, so this is a wording question for the authors.
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Wording Table 3 footnote: "Total normal initiations, 50%; pitch changes observed, 19%"; the prehead-polyhead column (91 (22) and 55 (12)) pools to 17% on the same basis that gives 50% for normal initiations.
- p. 13 Table 3 footnote a
pitch changes observed, 19%
- p. 13 Table 3, Prehead-polyhead column
91 (22)
- p. 13 Table 3, Prehead-polyhead column
55 (12)
Only the authors can say what is right here.
Judge's note: Table 3 on the p13 image reads: 20 min 129 (31), 91 (22), 155 (38), 36 (9), total 411; 60 min 146 (33), 14 (3), 55 (12), 192 (43), 41 (9), total 448. Pooled normal initiations come to 50.6%, matching the footnote's 50%. Pooled prehead-polyheads come to 17.0%, not 19%. Dropping the unclassified particles gives 18.7%, but on that basis normal initiations would be 55.6%. The footnote does not define how "pitch changes observed" was counted, and it may include observations beyond the prehead-polyhead column, so this is a question for the authors.
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Typo Methods cite "Stephen et al. (25)", but reference 25 is "Steven, A. C., U. Aebi, and M. K. Showe. 1976."
- p. 2 Methods, Electron microscopy
Stephen et al. (25)
- p. 18 Literature Cited, ref. 25
Steven, A. C., U. Aebi, and M. K. Showe. 1976.
- p. 2 Methods, Electron microscopy
described in Stephen et al. (25)
- p. 18 Reference 25
Steven, A. C., U. Aebi, and M. K. Showe.
Judge's note: The p2 image shows "Stephen et al. (25)" and the p18 image shows reference 25 with first author Steven. No author named Stephen is in the reference list. The reference number is correct; only the name is misspelt.
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Typo "Therefore, the 24- defect does not effect initiation as previously thought": 'effect' is printed where 'affect' is meant.
- p. 2 Introduction, final paragraph
defect does not effect initiation
- p. 2 Introduction, top of left column
defect does not effect initiation as previously
Judge's note: Confirmed on the p2 image (top of left column). The context (P24 acts late, not in initiation) requires 'affect'.
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Typo "in the Sorval SS34": the centrifuge name is printed 'Sorval' (the reviewer says the maker's name is 'Sorvall').
- p. 2 Methods, Isolation of mutant preheads
in the Sorval SS34
Only the authors can say what is right here.
Judge's note: Rests on outside knowledge: the manufacturer's name is spelled 'Sorvall'. The p2 image does print "Sorval SS34". Nothing in the files gives the correct spelling.
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Typo "the adsorbance was measured at 605 nm": 'adsorbance' is printed for 'absorbance'.
- p. 2 Methods, Quantitation from SDS gels
the adsorb- ance was measured at 605 nm
Judge's note: The p2 image shows "adsorb-ance" across a line break in the 'Quantitation from SDS gels' paragraph. An optical reading of eluted dye at 605 nm is an absorbance.
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Typo "decreased in proportion to the P22 and IpIII": the protein is printed 'IpIII' here but 'IPIII' elsewhere (e.g. "350 molecules of IPIII").
- p. 6 Results, left column below Fig. 2
P22 and IpIII
- p. 5 Results, right column
350 molecules of IPIII
Judge's note: The p6 image shows a lower-case p in "IpIII"; the p5 text and the figure labels use "IPIII". This is a capitalisation inconsistency only.
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Typo Fig. 8 legend: "(b) shows a mixture of gradient-purified 21(tsN8-), 23(tsA78), and 21(tsN8)": the double-mutant genotype is garbled; evidently "21(tsN8)-23(tsA78) and 21(tsN8)" is meant.
- p. 14 Fig. 8 legend
21(tsN8-), 23(tsA78), and 21(tsN8)
Judge's note: The p14 image shows the legend with a superscript minus inside the parenthesis and commas, so it reads as three components with 21(tsN8) listed twice. The same legend names panel (a) as "21(tsN8)-23(tsA78) preheads", and the arrows mark "the 21(tsN8) unexpanded preheads", so the intended mixture is the double mutant plus 21(tsN8).
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Typo Reference "15. Laemmli, U. K., and S. F. Quittner. 1974." appears in Literature Cited but is not cited anywhere in the text.
- p. 18 Literature Cited, ref. 15
15. Laemmli, U. K., and S. F. Quittner. 1974.
Judge's note: Viewed the crop of the reference list: entry 15 is present as quoted. Searched the text layer for a standalone 15, for "Quittner", for comma-separated citation lists containing numbers 10 to 19, and for numeric ranges that could span 15. The only hits for 15 are 0.15 M, 15,000 rpm, 15 to 40% gradients, 15°C, the 15,5 folding, a count of 15 particles and the reference entry itself; the only ranges are lysate names such as (21-22-23). No citation of reference 15 was found. Text-layer search could miss a citation garbled in extraction, so this is recorded as a minor uncited-reference observation.
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