Abstract: The invention relates to a method for producing a structured layer of defined functional molecules on the surface of a flat substrate, on the surface of which structures having different surface properties, at least as regards their hydrophobicity, are produced. A monolayer of a protein-containing crystalline cell surface layer (S layer) is deposited by recrystallization on said structured surface. Said S Layer binds only to those structured areas of the surface characterized by raised hydrophobicity. Alternatively, a structured S-layer may also be produced on the basis of a monolayer of an S layer deposited on a substrate by irradiating predefined sections of said layer to be structured with radiation of a predetermined intensity and energy. In the irradiated sections of the S-layer this suppresses the binding or intercalating ability of at least one surface.