ROR family

The receptor tyrosine kinase-like orphan receptors (ROR) family of receptor tyrosine kinases (RTKs) are type I transmembrane protein tyrosine kinases, characterized by their extracellular Frizzled-like cysteine-rich domains (CRDs) and membrane-proximal Kringle domains. RORs are originally identified as orphan receptor tyrosine kinases whose tyrosine kinase domains are highly similar to those of the Trk family. RORs are evolutionary conserved throughout the animal kingdom and act as alternative receptors and co-receptors of WNT ligands. In vertebrate, the Ror-family RTKs consist of two structurally related members, Ror1 and Ror2. The intracellular signaling cascades activated downstream of ROR receptors are diverse, including but not limited to ROR-Frizzled-mediated activation of planar cell polarity signaling, RTK-like signaling, and antagonistic regulation of WNT/β-Catenin signaling. RORs function in developmental processes including skeletal and neuronal development, cell movement and cell polarity.