Kremen (Kringle-containing protein marking the eye and the nose) proteins are type I transmembrane proteins that contain extracellular kringle, WSC and CUB domains and an intracellular region without any conserved motifs. Two related members, Kremen-1 and -2, have been identified. Kremens bind a subset of the secreted Dickkopf (Dkk) proteins with high affinity. The canonical Wnt signaling pathway receptor complex composed of Wnt, the seven-transmembrane domain receptor Frizzled, and the receptor-related protein 5/6 (LRP5/6) coreceptor, is modulated by Kremens and Dkk proteins.