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. 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. Additional site-directed mutagenesis experiments indicated that the tyrosine residues at positions 708, 710, 711, 713 and 715 are phosphorylation sites, whereas tyrosine at position 705 is not. Belongs to the etk/wzc family.