Involved in the biosynthesis of the macrolide antibiotic tylosin derived from the polyketide lactone tylactone. Catalyzes the transfer of alpha-D-mycaminosyl from dTDP-alpha-D-mycaminose to the 5-hydroxyl group of tylactone to yield 5-O-mycaminosytylactone. It can also accept 16-membered tylactone and 12-membered ring macrolide. dTDP-alpha-D-mycaminose + tylactone = 5-O-beta-D-mycaminosyltylactone + dTDP + H(+) The activity of TylM2 is substantially increased by the addition of the accessory protein TylM3. Antibiotic biosynthesis; tylosin biosynthesis. Belongs to the glycosyltransferase 28 family.