Involved in the pollen tube perception of the female signal. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with MDIS1 and LURE1.2. Expressed in pollen tubes. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. Truncated N-terminus.