http://www.creativebiomart.net/description_382932_12.htm

FZD4, also known as CD344, belongs to the the frizzle family. Members of this family encode seven-transmembrane domain proteins that are receptors for the Wingless type MMTV integration site family of signaling proteins. Most of frizzled receptors are coupled to the beta-catenin (CTNNB1) canonical signaling pathway, which leads to the activation of disheveled proteins, inhibition of GSK-3 kinase, nuclear accumulation of beta-catenin (CTNNB1) and activation of Wnt target genes. FZD4 is the receptor for Wnt proteins. In retina, it can be both activated by Wnt protein-binding, but also by a Wnt-independent signaling via binding of norrin, promoting in both cases beta-catenin (CTNNB1) accumulation and stimulation of LEF/TCF-mediated transcriptional programs. FZD4 plays a critical role in retinal vascularization by acting as a receptor for Wnt proteins and norrin.