I only know from experience that UA will NOT interline with TK on separate tickets,since you say your award is IAD to IST,I asume that your ADB is a separate ticket,in that case UA will not interline.However there are luggage facilities at international and domestic in IST,at least the one in international is open 24 hrs,its also closer to the metro station,which now is the best/fastest way to get down town,after they made the conection at Yenikapi for the Taksim area.
BTW : Bags generally gets to the carousel pretty fast in IST,but the imigration wait can be long,unless you have a Turkish passport,so you dont loose so much time.The left luggage is to your right after you exit customs.
Last edited by geirfugl; Nov 29, 2014 at 4:11 am