A substrate of transglutaminase, specific to the epidermis, was identified, by fluorescent and radioactive labelling with the lysine analogues dansylcadaverine and [14C]putrescine respectively, in newborn-rat epidermal homogenates and whole-skin organ cultures. The labelled analogues were preferentially incorporated into the stratum-corneum protein filaggrin in a Ca2+-dependent manner in both ‘in vitro’ systems. When filaggrin was labelled in vivo with [3H]histidine and then incubated with rat epidermal preparations, the label was rendered SDS/thiol-insoluble. Incorporation of [3H]filaggrin into the insoluble envelope fraction was Ca2+-dependent and inhibited by EDTA and exogenous amines. Antisera to newborn-rat filaggrin cross-reacted with purified newborn-rat cell envelopes, and this reaction was blocked by adsorbing the antiserum with purified filaggrin. Quantification of the ‘envelope-bound’ filaggrin showed it to be a significant component, accounting for approx. 10% of the cell-envelope protein.
Evidence for filaggrin as a component of the cell envelope of the newborn rat
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S Richards, I R Scott, C R Harding, J E Liddell, G M Powell, C G Curtis; Evidence for filaggrin as a component of the cell envelope of the newborn rat. Biochem J 1 July 1988; 253 (1): 153–160. doi: https://doi.org/10.1042/bj2530153
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