Secreted frizzled-related proteins
secreted frizzled-related proteins
The Secreted frizzled-related protein (SFRP) family consists of five secreted glycoproteins in humans (SFRP1, SFRP2, SFRP3 [FRZB], SFRP4, SFRP5) that act as extracellular signaling ligands. Each SFRP is around 300 amino acids in length and contains a cysteine-rich domain (CRD) that shares 30-50% sequence homology with the CRD of Frizzled (Fz) receptors. SFRPs are able to bind Wnt proteins and Fz receptors in the extracellular compartment.