Protein kinase which regulates promastigote proliferation in host macrophages, thereby playing an essential role in parasite virulence. ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Can use both Mg(2+) and Mn(2+) in vitro and shows higher activity with Mn(2+) but Mg(2+) is likely to be the in vivo cofactor. Active between 21 and 40 degrees Celsius. Expressed at promastigote stage but not in lesion-derived amastigotes (at protein level). Expressed during the differentiation of promastigotes to amastigotes in vitro. Homozygous deletion mutants grow slightly slower, but have no significant morphological abnormalities. In BALB/c mice, has reduced infectivity, which is characterized by a delayed and decelerated development of footpad lesions. Belongs to the protein kinase superfamily. STE Ser/Thr protein kinase family. MAP kinase kinase subfamily.