Catalyzes the ATP-dependent phosphorylation of maltose to maltose 1-phosphate (Probable). Is involved in a branched alpha-glucan biosynthetic pathway from trehalose, together with TreS, GlgE and GlgB. ATP + D-maltose = ADP + alpha-maltose 1-phosphate + H(+) Glycan biosynthesis; glycogen biosynthesis. Monomer. Cells lacking this gene display maltose accumulation. Belongs to the aminoglycoside phosphotransferase family.