Background of the antigen
Members of the STE-20 like kinase family are known to stimulate MAPK pathways by directly activating MAPKKK. LYK5 is a novel pseudokinase member of this family consisting of a STE-20 like kinase domain but lacks several residues that are required for its catalytic activity. It specifically binds LKB1 and plays a key role in regulating the tumor suppressor activities of LKB1. It functions as an upstream activator of LKB1 and also directs the sub-cellular localization of LKB1 by anchoring it in the cytoplasm. LYK5-LKB1 interaction results in phosphorylation of LYK5 and enhanced autophosphorylation of LKB1.
