title: In vitro assembly properties of human type I and II hair keratins.
abstract: Multiple type I and II hair keratins are expressed in hair-forming cells but the role of each protein in hair fiber formation remains obscure. In this study, recombinant proteins of human type I hair keratins (K35, K36 and K38) and type II hair keratins (K81 and K85) were prepared using bacterial expression systems. The heterotypic subunit interactions between the type I and II hair keratins were characterized using two-dimensional gel electrophoresis and surface plasmon resonance (SPR). Gel electrophoresis showed that the heterotypic complex-forming urea concentrations differ depending on the combination of keratins. K35-K85 and K36-K81 formed relatively stable heterotypic complexes. SPR revealed that soluble K35 bound to immobilized K85 with a higher affinity than to immobilized K81. The in vitro intermediate filament (IF) assembly of the hair keratins was explored by negative-staining electron microscopy. While K35-K81, K36-K81 and K35-K36-K81 formed IFs, K35-K85 afforded tight bundles of short IFs and large paracrystalline assemblies, and K36-K85 formed IF tangles. K85 promotes lateral association rather than elongation of short IFs. The in vitro assembly properties of hair keratins depended on the combination of type I and II hair keratins. Our data suggest the functional significance of K35-K85 and K36-K81 with distinct assembly properties in the formation of macrofibrils.
authors.affiliation: Department of Anatomy and Physiology, Faculty of Medicine, Saga University.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Honda
authors.forename: Kenzo
authors.initials: K
authors.lastname: Koike
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kubo
authors.forename: Sadahiko
authors.initials: S
authors.lastname: Masuko
authors.forename: Yuki
authors.initials: Y
authors.lastname: Arakawa
authors.forename: Shoji
authors.initials: S
authors.lastname: Ando
mesh_terms: D005786:Gene Expression Regulation; D006801:Humans; D053530:Keratins, Type I / Q000737:chemistry* / Q000378:metabolism*; D053531:Keratins, Type II / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D053530:Keratins, Type I; D053531:Keratins, Type II; D011994:Recombinant Proteins