FUNCTION Protein kinase involved in the transduction of mitogenic signals from the cell membrane to the nucleus (Probable). Phosphorylates MAP2K1, and thereby activates the MAP kinase signal transduction pathway (PubMed:21441910, PubMed:29433126). May play a role in the postsynaptic responses of hippocampal neurons (PubMed:1508179).ACTIVITY REGULATION 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.SUBUNIT 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-753. Heterodimerizes (via N-terminus) with KSR1 (via N-terminus) or KSR2 (via N-terminus) in a MAP2K1-dependent manner (PubMed:29433126). Interacts with MAP2K1 and MAP2K2 (PubMed:29433126). 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 (PubMed:19710016). Interacts with PRMT5 (PubMed:21917714). Interacts with KSR2 (PubMed:21441910). Interacts with AKAP13, MAP2K1 and KSR1. Identified in a complex with AKAP13, MAP2K1 and KSR1 (PubMed:21102438). Interacts with FNIP1 and FNIP2 (PubMed:27353360).TISSUE SPECIFICITY Brain and testis.PTM Phosphorylation at Ser-365 by SGK1 inhibits its activity.PTM Methylation at Arg-671 decreases stability and kinase activity.PTM Ubiquitinated by RNF149; which leads to proteasomal degradation. Polyubiquitinated at Lys-578 in response to EGF.DISEASE Defects in BRAF are found in a wide range of cancers.DISEASE A chromosomal aberration involving BRAF is found in pilocytic astrocytomas. A tandem duplication of 2 Mb at 7q34 leads to the expression of a KIAA1549-BRAF fusion protein with a constitutive kinase activity and inducing cell transformation.SIMILARITY Belongs to the protein kinase superfamily. TKL Ser/Thr protein kinase family. RAF subfamily.