Tyrosine-protein kinase that acts as cell-surface receptor for CSF1 and plays an essential role in the regulation of survival, proliferation and differentiation of hematopoietic precursor cells, especially mononuclear phagocytes, such as macrophages and monocytes. Plays an important role in innate immunity and in inflammatory processes. Plays an important role in the regulation of osteoclast proliferation and differentiation, the regulation of bone resorption, and is required for normal bone development. Promotes reorganization of the actin cytoskeleton, regulates formation of membrane ruffles, cell adhesion and cell migration. Activates several signaling pathways in response to ligand binding (By similarity). ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Present in an inactive conformation in the absence of bound ligand. CSF1 binding leads to dimerization and activation by autophosphorylation on tyrosine residues (By similarity). Monomer. Homodimer. Interacts with CSF1 (By similarity). The autophosphorylated receptor is ubiquitinated and internalized, leading to its degradation. The juxtamembrane domain functions as autoinhibitory region. Phosphorylation of tyrosine residues in this region leads to a conformation change and activation of the kinase (By similarity). The activation loop plays an important role in the regulation of kinase activity. Phosphorylation of tyrosine residues in this region leads to a conformation change and activation of the kinase (By similarity). Autophosphorylated in response to CSF1 binding. autophosphorylation, leading to its degradation. Ubiquitinated. Becomes rapidly polyubiquitinated after autophosphorylation, leading to its degradation (By similarity). Belongs to the protein kinase superfamily. Tyr protein kinase family. CSF-1/PDGF receptor subfamily.