Here is one source that may be helpful:
 {[cite book | title=Rome and the Eastern Churches | author=Nichols, Aidan; Nichols, Op | url=http://books.google.com/books?id=Hje62q52XNsC | pages=211–212}}
It discusses Justinian's designations of roles in the imperial church among Rome and Constinople in the 6th century.