The present invention relates to a novel library for the generation of muteins and to novel muteins derived from human lipocalin 2 (Lcn2, hNGAL) and related proteins that bind a given target with detectable affinity. The invention also relates to corresponding nucleic acid molecules encoding such a mutein and to a method for their generation. The invention further relates to a method for producing such a mutein. For example, such muteins may serve to bind and deplete pathological forms of natural biomolecules such as the amyloid beta peptide in Alzheimer's disease or may target the fibronectin extra-domain B, which is associated with tumor neovasculature.
