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Macrofibril assembly in trichocyte (hard alpha-) keratins
R D Bruce Fraser1, David A D Parry
1Institute of Fundamental Sciences, Massey University, Private Bag 11-222, Palmerston North, New Zealand.
Journal of Structural Biology
|April 26, 2003
Summary
Hard alpha-keratin fibers in wool and hair form macrofibrils through intermediate filament (IF) aggregation into sheets. This study formulates structural principles for IF sheet formation, crucial for understanding keratin fiber development.
Area of Science:
- Biochemistry
- Materials Science
- Cell Biology
Background:
- Trichocyte (hard alpha-) keratin fibers possess a composite structure.
- Intermediate filaments (IF) are embedded within a sulfur-rich protein matrix.
- IF aggregate into macrofibrils, with sheet formation being a key initial step.
Purpose of the Study:
- To formulate the structural principles governing intermediate filament (IF) sheet formation in hard alpha-keratin fibers.
- To propose specific models for the interaction between neighboring IF within these sheets.
- To provide a generalizable mechanism for keratin fiber development.
Main Methods:
- Analysis of existing X-ray diffraction data.
- Interpretation of electron microscope images of keratin fibers.
- Evaluation of crosslinking data.
Main Results:
- Structural principles for IF sheet formation have been formulated.
- Models for IF interactions within sheets are proposed.
- The proposed mechanism explains the filament/matrix texture observed in trichocyte keratins.
Conclusions:
- The proposed mechanism for IF sheet formation offers a generalizable explanation for the structure of hard alpha-keratin fibers.
- Understanding IF aggregation is key to comprehending wool and hair development.
- This research provides insights into the fundamental assembly of keratinous materials.