P9  CHEMICAL COMPOSITION OF THE HAIR CUTICLE: CORNIFIED ENVELOPE (CE) PROTEINS IN EPICUTICLE AND A-LAYER

H. Zahn, F.-J. Wortmann, H., Deutsches Wollforschungsinstitut an der RWTH Aachen, Germany

1.    Today’s opinions on the chemical composition of the morphological components of the cuticle are presented.

2.    The high isodipeptide content of the A-layer and its contrast in transmission electron micrographs proves it to be a mixture of high sulfur and CE proteins. The CE proteins loricrin and involucrin are identified by their unusual amino acid compositions and their respective content calculated quantitatively.

3.    An additional CE protein, the small proline-rich protein, is found in the resistant membrane of the cuticle. Its amino acid composition is similar to that of the CE of cultured human epidermal keratinocytes. [P.M. Steinert and L.N. Marekov, J. Biol. Chem. 272, 2021-2030 (1997); N.A. Robinson et al., J. Biol. Chem. 272, 12035-12046 (1997)].

As a result it is postulated that the resistant membrane is an early and the A-layer a mature CE and that A-layer and epicuticle are thus to be described as CE.