I have experience of TK to TK connection on seperate bookings. Both the times I was offered interline transfer all the way if I decided to check in my carry on. I declined.
you will need to clear transit security, as others have mentioned. They will ask for boarding pass before you can do it. If your OLCI didnt work, there's a TK transfer desk just opposite to the transit security. They issued me my boarding pass the time i couldn't get my olci complicated.