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Structural Hierarchy of Trichocyte Keratin Intermediate Filaments

  • R. D. Bruce Fraser
  • David A. D. ParryEmail author
Chapter
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 1054)

Abstract

Although trichocyte keratins (hair, wool, quill, claw) have been studied since the 1930s it is only over the last 30 years or so that major advances have been made in our understanding of the complex structural hierarchy of the filamentous component of this important filament-matrix composite. A variety of techniques, including amino acid sequence analysis, computer modelling, X-ray fibre diffraction and protein crystallography, various forms of electron microscopy, and crosslinking methods have now combined to reveal much of the structural detail. The heterodimeric structure of the keratin molecule is clear, as are the highly-specific modes by which these molecules aggregate to form functionally viable IF. The observation that hair keratin can adopt not one but two structurally-distinct conformations, one formed in the living cells at the base of the hair follicle in a reducing environment and the second in the fully differentiated hair in dead cells in an oxidized state, was unexpected but has major implications for the mechanism of hair growth. Insights have also been made into the mechanism of the uppermost level of hair superstructure, relating to the assembly of the IF in the paracortical and orthocortical macrofibrils.

Keywords

Filament-matrix composite Structural transition in trichocyte keratin X-ray diffraction of keratin fibres Molecular assembly Disulfide bonds DST crosslinks 

Abbreviations

IF

intermediate filament

KAP

keratin-associated proteins

DST

disulfo-succinimidyl tartrate

ULF

unit-length-filament

HIM

helix initiation motif

HTM

helix termination motif

TEM

transmission electron microscopy

STEM

scanning transmission electron microscopy

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© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  1. 1.Institute of Fundamental SciencesMassey UniversityPalmerston NorthNew Zealand
  2. 2.TewantinAustralia
  3. 3.Riddet InstituteMassey UniversityPalmerston NorthNew Zealand

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