Serine/threonine kinase involved in negative regulation of chemotaxis. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Up-regulated by cAMP. Translocates very rapidly to the plasma membrane upon stimulation by chemoattractant, but no polarized localization to the leading edge in aggregating cells. Very low expression in vegetative cells, but increases dramatically at 4 hours after starvation and then rapidly falls to very low levels throughout the remainder of development. The RGS domain is involved in translocation to the plasma membrane. Autophosphorylated. RckA kinase activity remains elevated unless the stimulus is removed and the kinase function is directly involved in delocalizing the protein from the plasma membrane. However, the membrane localization does not require a functional kinase domain and seems not to be essential for the kinase activation. Belongs to the protein kinase superfamily. TKL Ser/Thr protein kinase family.