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Annotated references for inclusion with web version of the review
Arai KM, Takahashi R, Yokote Y, Akahane K (1986) The primary structure of feather
keratin from duck (Anas platyrhynchos) and pigeon (Columba livia). Biochim Biophys
Acta 873: 6-12
The amino acid sequences from duck and pigeon feather keratins are provided
Astbury WT, Marwick TC (1932) X-ray interpretation of the molecular structure of
feather keratin. Nature (London) 130: 309-310
The earliest structural research on feather keratin was carried out by Astbury and
colleagues at Leeds, and this paper helped establish the field
Astbury WT, Woods HJ (1933) X-ray studies on the structure of hair, wool and related
fibres II: the molecular structure and elastic properties of hair keratin. Phil Trans Roy Soc
A232: 333-394
Chains in the -form were shown to pack in antiparallel sheets with three-dimensional
regularity
Astbury WT, Dickson S, Bailey K (1935) The X-ray interpretation of denaturation and
the structure of the seed globulins. Biochem J 29: 2351-2360
The cross- conformation was initially proposed on X-ray data derived from denatured
globular proteins. In the cross- structure the chains are oriented perpendicular to the
fibre axis
Alibardi L, Dalla Valle L, Nardi, A et al (2008) Evolution of hard proteins in sauropsid
integument in relation to cornification of skin derivatives in amniotes. J Anat (in press)
The distribution and variability of the residues in the conserved region of all -keratins
has been analysed
Bear RS, Rugo HJ (1951) The results of X-ray diffraction studies on keratin fibers. Ann
NY Acad Sci 53: 627-648.
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Understanding the X-ray diffraction pattern from feather keratin was greatly assisted by
destroying the longitudinal and rotational correlation between filaments using
mechanical treatments.
Chothia C, Janin J (1981) Relative orientation of close-packed β-pleated sheets in
proteins. Proc Natl Acad Sci 78:4146-4150
When β-pleated sheets pack face-to-face the angle between the strand directions is
generally about -30º
Conway JK, Parry DAD (1988) Intermediate filament structure 3. Analysis of sequence
homologies. Int J Biol Macromol 10: 79-98
A study of the sequences of all intermediate filament chains illustrates the conserved and
repeating sequences that are present. Amongst the quasi-repeats is the apolar-X
sequence repeated four times consecutively in linker L12
Dalla Valle L, Nardi A, Gelmi C et al (2008) -keratins of the crocodilian epidermis:
composition, structure, and phylogenetic relationships. J Exp Zool 310B: 1-16
The amino acid sequences of crocodile -keratins have been determined, analysed and
compared with other members of the feather keratin-like family
Dalla Valle L, Nardi A, Toni M et al (2009) Beta-keratins of turtle shell are glycineproline-tyrosine rich proteins similar to those of crocodilians and birds. J Anat (in press)
A large number of turtle shell -keratin sequences are reported. Each contains a common
32-residue sequence believed to form the -sheet core of the feather keratin-like filaments
Filshie BK, Fraser RDB, MacRae TP et al (1964) X-ray diffraction and electronmicroscope observations on soluble derivatives of feather keratin. Biochem J 92: 19
A cross- conformation was observed using X-ray data obtained from oriented films of
solubilised feather keratin. Electron microscope observations showed filaments about 4
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nm in diameter that were twisted around one another in pairs and assembled into sheets.
The filaments can be considered as amyloid-like.
Filshie BK, Rogers GE (1962) An electron microscope study of the fine structure of
feather keratin. J Cell Biol 13: 1-12
This work still represents some of the most detailed electron microscope observations
available for feather keratin. These show approximately circular filaments about 3-4 nm
in diameter
Fraser RDB, MacRae TP (1963) Structural organization in feather keratin. J Mol Biol 7:
272-280
Improved methods of destroying the longitudinal and rotational correlation between
filaments by mechanical treatment resulted in a simplified X-ray pattern characteristic of
a helical structure
Fraser RDB, MacRae TP (1973) Conformation in Fibrous Proteins and Related Synthetic
Polypeptides. Academic, New York
At the time this was the most comprehensive compilation of data available on both
fibrous proteins and the methodology used to study them. It still provides an excellent
summary on the structures of many of the synthetic polypeptides that were used as model
protein systems. This includes those giving rise to a cross-β conformation
Fraser RDB, MacRae TP (1976) The molecular structure of feather keratin. Proc 16th Int
Ornith Congress, Canberra, pp 443-451
A further refinement of the feather keratin model presented five years earlier in which strands and -turns have been identified in a 32-residue segment of sequence
Fraser RDB, Parry DAD (1996) The molecular structure of reptilian keratin. Int J Biol
Macromol 19: 207-211
The analysis of a lizard claw protein reveals the common structural features of the
filaments in avian and reptilian keratins
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Fraser RDB, Parry DAD (2008) Molecular packing in the feather keratin filament. J
Struct Biol 162: 1-13
This is the latest and most comprehensive model yet derived for the core of the feather
keratin filament. It shows close packing, facilitated by predominately apolar interactions,
between twisted, antiparallel -sheets. A highly conserved 32-residue sequence exists
across the entire family of feather keratin-like proteins and is postulated to provide a
four-stranded antiparallel -sheet structure
Fraser RDB, MacRae TP, Parry DAD et al (1969) The structure of -keratin. Polymer 10:
810-826
Analysis of X-ray diffraction patterns from hard -keratin subjected to stretching in
steam revealed a planar, antiparallel -sheet conformation
Fraser RDB, MacRae TP, Parry DAD et al (1971) The structure of feather keratin.
Polymer 12: 35-56
This paper reported the first detailed model of feather keratin. It accounted for the
simplified X-ray diffraction pattern in terms of twisted -sheets, a unique structural form
at that time
Gillespie JM (1990) The proteins of hair and other hard -keratins. In Goldman RD,
Steinert PM (eds) Cellular and molecular biology of intermediate filaments, Plenum
Press: New York-London, pp 95-128
A detailed description is provided of the various families of proteins that together
constitute the mammalian hard -keratins
Gregg K, Wilton SD, Parry DAD et al (1984) A comparison of genomic sequences for
feather and scale keratins: structural and evolutionary implications. EMBO J 3:175-178
The key difference between the sequences of feather and scale keratins is shown to reside
in the presence in scale but not in feather of a four-fold 13-residue repeat thought to
adopt an antiparallel -sheet conformation
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Inglis A, Gillespie JM, Roxburgh C, Whittaker L and Casagranda F (1987) Sequence of a
glycine-rich protein from lizard claw: unusual dilute acid and heptafluorobutyric acid
cleavage. In L’Italien (ed) Protein, structure and function, Plenum Press: New YorkLondon, pp 757-764
The first reptilian keratin to be sequenced was from a lizard claw and the sequence
showed similarities to those from feather keratins
Kajava AV, Squire JM, Parry DAD (2006) -Structures in fibrous proteins. Adv Prot
Chem 73: 1-15
Variants of the classical -structures – the -solenoid, the triple-stranded -solenoid, the
cross -prism, the triple -spiral and the spiral -hairpin staircase – are all described
Kamiya H, Ishii C, Ogawa T et al (2002) Crystal structure of a conger eel galectin
congerin II at 1.45Å resolution: implication for the accelerated evolution of a new ligandbinding site following gene duplication J Mol Biol 321: 879-889
The pair of twisted -sheets seen in Congerin II are believed to be packed in a manner
closely analogous to that in feather keratin
Marwick TC (1931) The X-ray classification of epidermal proteins. J Text Sci 4, 31-33
This is now mainly of historical interest but it does provide some of the earliest X-ray
data available on feather keratin and indicates an extended structure commonly referred
to as the -strand
O'Donnell IJ (1973) The complete amino acid sequence of a feather keratin from emu
(Dromanus novae-hollandiae) Aust J Biol Sci 26: 415-437
This is the first amino acid sequence from a feather keratin protein (emu). Feather was
also shown to contain only a single protein component compared with mammalian
keratins which contain three families of proteins each with multiple components
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O’Donnell IJ, Inglis AS (1974) Amino acid sequence of a feather keratin from silver gull
(Larus Novae-Hollandiae) and comparison with one from emu (Dromaius NovaHollandiae) Aust J Biol Sci 27: 369-382
The sequence of a second feather keratin protein (seagull) is compared with that from
emu
Parker KD, Rudall KM (1957) Structure of the silk of chrysopa egg-stalks. Nature
(London) 179: 905-906
This describes the cross-β-conformation from a naturally-occurring material - the egg
stalk from the green lacewing fly
Parry DAD, Fraser RDB (1985) Intermediate filament structure 1. Analysis of IF protein
sequence data. Int J Biol Macromol 7: 203-213
A central linker in keratin intermediate filament chains (linker L12) has a four
consecutive dipeptide repeats with apolar residues in alternate positions. The possibility
that this might form a short length of -structure has been suggested
Parry DAD, North ACT (1998) Hard -keratin intermediate filament chains: substructure
of the N- and C-terminal domains and the predicted structure and function of the Cterminal domains of type I and II chains. J Struct Biol 122: 67-75
The sequence immediately C-terminal to the rod domain in keratin intermediate filament
chains is predicted to form a four-stranded antiparallel pleated -sheet. One face would
be largely composed of apolar residues
Parry DAD, Marekov LN, Steinert PM et al (2002) A role for the 1A and L1 rod domain
segments in head domain organization and function of intermediate filaments: Structural
analysis of trichocyte keratin. J Struct Biol 137: 97-108
The head domains of trichocyte keratin Type II intermediate filament chains contain four
contiguous (imperfect but highly homologous) nonapeptide repeats that are predicted to
form a four-stranded antiparallel -sheet. This region may interact with the equivalent
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region in a head domain from a neighbouring filament thereby specifying interfilament
interactions
Pauling L, Corey RB (1951). The pleated sheet, a new layer configuration of polypeptide
chains. Proc Natl Acad Sci USA 37: 251-256
This provided the first detailed description of the element of secondary structure known
as the -strand. It also provided a model of how these could be packed to form an
antiparallel sheet-like structure stabilized by hydrogen bonds.
Presland RB, Gregg K, Molloy PL et al (1989) Avian keratin genes. I. A molecular
analysis of the structure and expression of a group of feather keratin genes. J Mol Biol
209: 549-559
This paper reports the amino acid sequence of chicken feather keratin
Richardson JS, Richardson DC (2002). Natural β-sheet proteins use negative design to
avoid edge-to-edge aggregation. Proc Natl Acad Sci USA 99: 2754-2760
Unwanted edge-to-edge aggregation of β-sheets can be prevented by the presence of
particular amino acids, often charged ones, in either the first or last β-strands
Rougvie MA (1954). Ph.D. Thesis, Massachusetts Institute of Technology
Feather keratin was solubilised by cleaving the disulphide bonds. Following chemical
modification of the cysteine residues the material was made into oriented films. X-ray
diffraction studies on this material indicated a filamentous structure similar to that
present in vivo
Sawyer RH, Washington LD, Salvatore BA et al (2003) Origin of archosaurian
integumentary appendages: the bristles of the wild turkey beard express feather-type 
keratins. J Exp Zool (Mol Dev Evol) 297B: 27-34
The turkey vulture bristle sequence is shown to have strong similarities to feather keratin
in a 30-40 residue region
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Schor R, Krimm S (1961) Studies on the structure of feather keratin II. A -helix model
for the structure of feather keratin. Biophys J 1: 489-515
This provides an early model for feather keratin based around the presence of -strands
Stewart M (1977) The structure of chicken scale keratin. J Ultrastruct Res 60:27-33
X-ray diffraction studies on the unique 52-residue sequence (the four-fold 13-residue
motif) present in scale but not in feather keratin indicates a β-conformation
Toni M, Dalla Valle L, Alibardi L. (2007a) The epidermis of scales in gecko lizards
contains multiple forms of -keratins including basic glycine-proline-serine-rich proteins.
J Proteome Res 6: 1792-1805
The sequences of β-keratins from gecko skin are listed and analysed
Toni M, Dalla Valle L, Alibardi L. (2007b) Hard (-) keratins in the epidermis of
reptiles: Composition, sequence, and molecular organization. J Proteome Res 6: 33773392
The sequences of some snake and lizard skin β-keratins are presented and analysed
Walker ID, Bridgen J (1976) The keratin chains of avian scale tissue. J Biochem 67: 283293
The amino acid sequence of chicken scale keratin is reported
Whitbread LA, Gregg K, Rogers GE (1991) The structure and expression of a gene
encoding chick claw keratin. Gene, 101: 223-229
The amino acid sequence of chicken claw keratin is reported