Catalyzes the transfer of the gamma-phosphate of ATP to D-galactose to form alpha-D-galactose-1-phosphate (Gal-1-P). To a lesser extent, is also able to phosphorylate 2-deoxy-D-galactose and D-galactosamine. Is not able to use D-galacturonic acid, D-talose, L-altrose, and L-glucose as substrates. alpha-D-galactose + ATP = ADP + alpha-D-galactose 1-phosphate + H(+) kcat is 108 min(-1), 30 min(-1) and 11.7 min(-1) with D-galactose, 2-deoxy-D-galactose, and D-galactosamine as substrate, respectively. Carbohydrate metabolism; galactose metabolism. Belongs to the GHMP kinase family. GalK subfamily.