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![Click on image for an interactive view with Cn3D](https://www.ncbi.nlm.nih.gov/Structure/cdd/cdThumbnail.cgi?uid=270659)
Catalytic domain of the Protein Tyrosine Kinase, Tyro3 PTKs catalyze the transfer of the gamma-phosphoryl group from ATP to tyrosine (tyr) residues in protein substrates. Tyro3 (or Sky) is predominantly expressed in the central nervous system and the brain, and functions as a neurotrophic factor. It is also expressed in osteoclasts and has a role in bone resorption. Tyro3 is a member of the TAM subfamily, composed of receptor PTKs (RTKs) containing an extracellular ligand-binding region with two immunoglobulin-like domains followed by two fibronectin type III repeats, a transmembrane segment, and an intracellular catalytic domain. Binding to their ligands, Gas6 and protein S, leads to receptor dimerization, autophosphorylation, activation, and intracellular signaling. The Tyro3 subfamily is part of a larger superfamily that includes the catalytic domains of other kinases such as serine/threonine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase.
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