What is the working mechanism of MAP Kinases?

When both tyrosine and threonine residues are phosphorylated, MAP kinase activity will be the maximum. This reveals the fact that MAP kinases act as switch kinases. The role of these switch kinases is to transmit information of increased intracellular tyrosine phosphorylation to that of serine/threonine phosphorylation. MAP kinases are yet not the direct substrates for RTKs nor receptor associated tyrosine kinases but are actually activated by an additional class of kinases termed MAP kinase kinases (MAPK kinases) and MAPK kinase kinases (MAPKK kinases).

Proto-oncogenic serine/threonine kinase, Raf is one among the prominent MAPK kinases. The final targets of the MAP kinases are several transcriptional regulators like serum response factor (SRF), and the proto-oncogenes Fos, Myc and Jun. The terminal targets also include the members of the steroid/thyroid hormone receptor super family of proteins.

Source and further information:- www.examville.com