An isolated peptide from skin aspartic protease (SASPase) or filaggrin-2 (FLG2), a fragment or homologue thereof, which can modify the three-dimensional shape of a complex formed by interaction between a first amino acid sequence from filaggrin-2 and a second amino acid sequence from SASPase, is described. The isolated peptide is useful as a target for screening for cosmetic or therapeutic active agents with regard to the skin and/or its appendages.
