The present invention relates to biologically active proteins comprising at least two domains wherein a first domain of said at least two domains comprises an amino acid sequence having and/or mediating said biological activity and a second domain of said at least two domains comprises an amino acid sequence consisting preferably of at least about 100 amino acid residues forming a random coil conformation whereby said random coil conformation mediates an increased in vivo and/or in vitro stability of said biologically active protein. Furthermore, nucleic acid molecules encoding the inventive biologically active proteins and vectors and cells comprising said nucleic acid molecules are disclosed. In addition, the present invention provides for compositions comprising the compounds of the invention as well as for specific uses of the biologically active proteins, nucleic acid molecules, vectors and cells of the invention.
