Involved in the transduction of mitogenic signals from the cell membrane to the nucleus. Phosphorylates MAP2K1, and thereby activates the MAP kinase signal transduction pathway. May play a role in the postsynaptic responses of hippocampal neurons. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Binds 2 Zn(2+) ions per subunit. In quiescent cells, maintained in an inactive state via an intramolecular interaction between the protein kinase and N-terminal domains. Following mitogen-mediated cell activation, binds via its RGB domain to active HRAS (GTP-bound) which releases the inhibitory intramolecular interaction between the two domains. This allows the MAP2K1-mediated dimerization of KSR1 or KSR2, and BRAF which activates BRAF. Monomer. Homodimer. Heterodimerizes with RAF1, and the heterodimer possesses a highly increased kinase activity compared to the respective homodimers or monomers. Heterodimerization is mitogen-regulated and enhanced by 14-3-3 proteins. MAPK1/ERK2 activation can induce a negative feedback that promotes the dissociation of the heterodimer by phosphorylating BRAF at Thr-738. Heterodimerizes (via N-terminus) with KSR1 (via N-terminus) or KSR2 (via N-terminus) in a MAP2K1-dependent manner (By similarity). Interacts with MAP2K1 and MAP2K2 (By similarity). Found in a complex with at least BRAF, HRAS, MAP2K1, MAPK3 and RGS14. Interacts with RIT1. Interacts (via N-terminus) with RGS14 (via RBD domains); the interaction mediates the formation of a ternary complex with RAF1, a ternary complex inhibited by GNAI1 (By similarity). Interacts with DGKH (By similarity). Interacts with PRMT5 (By similarity). Interacts with AKAP13, MAP2K1 and KSR1. Identified in a complex with AKAP13, KSR1 and MAP2K1 (PubMed:21102438). Interacts with FNIP1 and FNIP2 (By similarity). Colocalizes with RGS14 and RAF1 in both the cytoplasm and membranes. Phosphorylation at Ser-348 by SGK1 inhibits its activity. Methylation by PRMT5 decreases stability and kinase activity. Ubiquitinated by RNF149; which leads to proteasomal degradation. Polyubiquitinated at Lys-615 in response to EGF (By similarity). Participates in a chromosomal translocation that produces a Tif1a-BRAF (T18) oncogene originally isolated from a furfural-induced hepatoma. Belongs to the protein kinase superfamily. TKL Ser/Thr protein kinase family. RAF subfamily. Chimeric cDNA.