When we sold our MA plate car we and the purchaser simply went to the Noter with all the paperwork including the insurance, we each signed a document (don't sign until you have the money) (the best was to get the moeny is to have him/her transfer by mobile into your account, and then check that it has arrived by mobile whilst in the noters). then it is up to him/her to sort out the plate change at the trafik dept. I hope it goes well for you.
As of April 2nd 2018 the system changed slightly. As stated above the Noter does all the transfer of ownership etc,but instead of going to the Trafic Polis for the change of plates now the new owner goes to the local Chamber of Drivers/Şoförler Odası for the number plates [plaka] to be issued (subject to a fee).
The system then prints the new car/motorbike papers. With this document, the new owner can purchase the compulsory traffic insurance.