Involved in the final steps of cytoplasmic maturation of the 40S ribosomal subunit (By similarity). In vitro, has strong ATPase activity and only low protein kinase activity (PubMed:24948609). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Autophosphorylated. Belongs to the protein kinase superfamily. RIO-type Ser/Thr kinase family.