Enables glycerol kinase activity. Involved in glycerol-3-phosphate biosynthetic process. Predicted to be located in cytosol and nucleus. Predicted to be active in mitochondrion. Is expressed in several structures, including adult head; embryonic/larval midgut; embryonic/larval midgut primordium; and spermatozoon. Used to study glycerol kinase deficiency. Human ortholog(s) of this gene implicated in glycerol kinase deficiency. Orthologous to human GK (glycerol kinase); GK2 (glycerol kinase 2); and GK3 (glycerol kinase 3).