Part of the UhpABC signaling cascade that controls the expression of the hexose phosphate transporter UhpT. UhpB functions as a membrane-associated protein kinase that autophosphorylates in response to interaction with UhpC, and subsequently transfers its phosphate group to the response regulator UhpA. Can also dephosphorylate UhpA. ATP + protein L-histidine = ADP + protein N-phospho-L-histidine. Autophosphorylated.