Required for the extracellular polysaccharide colanic acid synthesis. The autophosphorylated form is inactive. Probably involved in the export of colanic acid from the cell to medium. Phosphorylates udg (By similarity). ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Dephosphorylated and activated by wzb. Glycan metabolism; exopolysaccharide biosynthesis. Autophosphorylated. Seems to be phosphorylated through a cooperative two-step mechanism. First, Tyr-569 is phosphorylated in an intramolecular reaction that generates a significant increase of protein kinase activity. Then Tyr-708, Tyr-710, Tyr-711, Tyr-713 and Tyr-715 are phosphorylated in an intermolecular Tyr-569-dependent reaction (By similarity). Belongs to the etk/wzc family.