The present invention relates to novel muteins derived from human tear lipocalin which bind to IL 4 receptor alpha. The sequences of the muteins comprise particular combinations of amino acids. In particular a mutated amino acid residue is present at any one or more of the sequence positions 27 28 30 31 33 53 57 61 64 66 80 83 104 106 and 108 of the linear polypeptide sequence of the mature human tear lipocalin. A mutated amino acid residue is also present at any 2 or more of the sequence positions 26 32 34 55 56 58 and 63 of the linear polypeptide sequence of the mature human tear lipocalin. The invention also provides a corresponding nucleic acid molecule encoding such a mutein and a method for producing such a mutein and its encoding nucleic acid molecule.
