We used developing human hair follicle cells for the isolation of hard alpha-keratin structural components. Intracellular dispersions examined by electron microscopy contained both individual alpha-keratin filaments and the tactoid-like filament assemblies observed in situ organized along subfibrillar arms of macrofibrils. The assemblies of average width 47 nm were composed of closely packed alpha-keratin filaments and originated from the initial filament arrays observed in sections of developing mammalian hair follicles. We have distinguished two types of assemblies: the para-like or hexagonally packed and the ortho-like spiral or whorl type. Axial banding extended across the width of filament assemblies, which suggested that hard alpha-keratin filaments pack in lateral register and form a lattice that contains interfilamentous bridges. We observed axial banding patterns with periods ranging from 20 to 22 nm, consistent with the 22-nm periodic structure deduced from x-ray diffraction studies and present in models proposed for hard alpha-keratin and other intermediate filaments. Preliminary biochemical studies of filaments and filament assemblies indicate that they consist of the closely related group of proteins (low-sulfur proteins) ubiquitous among extracts of hard mammalian keratins. Isolated hard alpha-keratin filament assemblies provide a new and valuable structural entity for investigating the assembly mechanisms involved in the formation of the filament-matrix framework found in hard mammalian keratin appendages.
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Article| October 01 1985
Isolation of intermediate filament assemblies from human hair follicles.
L N Jones
F M Pope
Online ISSN: 1540-8140
Print ISSN: 0021-9525
J Cell Biol (1985) 101 (4): 1569–1577.
L N Jones, F M Pope; Isolation of intermediate filament assemblies from human hair follicles.. J Cell Biol 1 October 1985; 101 (4): 1569–1577. doi: https://doi.org/10.1083/jcb.101.4.1569
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