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Catalytic domain of the Protein Tyrosine Kinase, Receptor tyrosine kinase-like Orphan Receptor 1 PTKs catalyze the transfer of the gamma-phosphoryl group from ATP to tyrosine (tyr) residues in protein substrates. Ror kinases are expressed in many tissues during development. Avian Ror1 was found to be involved in late limb development. Studies in mice reveal that Ror1 is important in the regulation of neurite growth in central neurons, as well as in respiratory development. Loss of Ror1 also enhances the heart and skeletal abnormalities found in Ror2-deficient mice. Ror proteins are orphan receptor PTKs (RTKs) containing an extracellular region with immunoglobulin-like, cysteine-rich, and kringle domains, a transmembrane segment, and an intracellular catalytic domain. Ror RTKs are unrelated to the nuclear receptor subfamily called retinoid-related orphan receptors (RORs). RTKs are usually activated through ligand binding, which causes dimerization and autophosphorylation of the intracellular tyr kinase catalytic domain. The Ror1 subfamily is part of a larger superfamily that includes the catalytic domains of other kinases such as protein serine/threonine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.
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