Catalyzes the transfer of a ribosyl phosphate group from 5-phosphoribose 1-diphosphate to orotate, leading to the formation of orotidine monophosphate (OMP) (By similarity). MATTSQLPAYKQDFLKSAIDGGVLKFGSFELKSKRISPYFFNAGEFHTARLARRIASAFAKTIIEAQEKAGLEFDIVFGPAYKGIPLCSAITIKLGDVAPQNLDRVSYSFDRKEAKDHGEGGNIVGASLKGKRVLIVDDVITAGTAKRDAIEKITKEGRHRRGIVVALDRMEKLPAADGDDSKPGPSAIGELRKEYGIPIFAILTLDDIIDGMKGFATPEDIKNTEDYRAKYKATD PYRE_HYPJE Orotate phosphoribosyltransferase ura5 236