Tyrosine-protein kinase that acts as cell-surface receptor for the cytokine KITLG/SCF and plays an essential role in the regulation of cell survival and proliferation, hematopoiesis, stem cell maintenance, gametogenesis, mast cell development, migration and function, and in melanogenesis. In response to KITLG/SCF binding, KIT can activate several signaling pathways. Phosphorylates PIK3R1, PLCG1, SH2B2/APS and CBL. Activates the AKT1 signaling pathway by phosphorylation of PIK3R1, the regulatory subunit of phosphatidylinositol 3-kinase. Activated KIT also transmits signals via GRB2 and activation of RAS, RAF1 and the MAP kinases MAPK1/ERK2 and/or MAPK3/ERK1. Promotes activation of STAT family members STAT1, STAT3, STAT5A and STAT5B. Activation of PLCG1 leads to the production of the cellular signaling molecules diacylglycerol and inositol 1,4,5-trisphosphate. KIT signaling is modulated by protein phosphatases, and by rapid internalization and degradation of the receptor. Activated KIT promotes phosphorylation of the protein phosphatases PTPN6/SHP-1 and PTPRU, and of the transcription factors STAT1, STAT3, STAT5A and STAT5B. Promotes phosphorylation of PIK3R1, CBL, CRK (isoform Crk-II), LYN, MAPK1/ERK2 and/or MAPK3/ERK1, PLCG1, SRC and SHC1 (By similarity). ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Present in an inactive conformation in the absence of bound ligand. KITLG/SCF binding leads to dimerization and activation by autophosphorylation on tyrosine residues. Activity is down-regulated by PRKCA-mediated phosphorylation on serine residues (By similarity). Monomer in the absence of bound KITLG/SCF. Homodimer in the presence of bound KITLG/SCF, forming a heterotetramer with two KITLG/SCF molecules. Interacts (via phosphorylated tyrosine residues) with the adapter proteins GRB2 and GRB7 (via SH2 domain), and SH2B2/APS. Interacts (via C-terminus) with MPDZ (via the tenth PDZ domain). Interacts (via phosphorylated tyrosine residues) with PIK3R1 and PIK3CD. Interacts (via phosphorylated tyrosine) with CRK (isoform Crk-II), FYN, SHC1 and MATK/CHK (via SH2 domain). Interacts with LYN and FES/FPS. Interacts (via phosphorylated tyrosine residues) with the protein phosphatases PTPN6/SHP-1 (via SH2 domain), PTPN11/SHP-2 (via SH2 domain) and PTPRU. Interacts with PLCG1. Interacts with DOK1 and TEC. Interacts with IL1RAP (independent of stimulation with KITLG/SCF). A mast cell-specific KITLG/SCF-induced interleukin-33 signaling complex contains IL1RL1, IL1RAP, KIT and MYD88 (By similarity). Ubiquitinated by SOCS6. KIT is rapidly ubiquitinated after autophosphorylation induced by KITLG/SCF binding, leading to internalization and degradation. Autophosphorylated on tyrosine residues. KITLG/SCF binding promotes autophosphorylation. Phosphorylated tyrosine residues are important for interaction with specific binding partners (By similarity). Numerous proteins are phosphorylated in response to KIT signaling, but it is not evident to determine which are directly phosphorylated by KIT under in vivo conditions. Belongs to the protein kinase superfamily. Tyr protein kinase family. CSF-1/PDGF receptor subfamily.