<p> Tagatose-6-phosphate kinase (<db_xref db="EC" dbkey="2.7.1.144"/>) is part of the tagatose-6-phosphate pathway of lactose degradation. <reaction> ATP + D-tagatose 6-phosphate = ADP + D-tagatose 1,6-bisphosphate </reaction>The genes coding for the enzymes of the tagatose 6-phosphate pathway have been found to be part of the lac operon together with thegenes coding for the lactose-phosphotransferase system and the phospho-beta-galactosidase in <taxon tax_id="1358">Lactococcus lactis</taxon>, Staphlococcus aureus, and <taxon tax_id="1309">Streptococcus mutans</taxon>. </p>