aldehydo-D-galactose 6-phosphate = keto-D-tagatose 6-phosphate Carbohydrate metabolism; D-galactose 6-phosphate degradation; D-tagatose 6-phosphate from D-galactose 6-phosphate: step 1/1. Heteromultimeric protein consisting of LacA and LacB. Belongs to the LacAB/RpiB family.