Its odd to think that 2 products owned by the same company for many years still have issues talking to each other?
Anyway, that a side MediaComposer 5.5 gave you the ability to exchange locators and marker information. But to be honest this does rely on you having the latest versions of both MediaComposer and ProTools and if the ProTools systems is owed by a third party then this all becomes a little out of your control.
So here's a guide to show you how to use a small (free) application that enables you to get the locator information out of ProTools and then convert this into a Tab Delimited File so that you can import this into MediaComposer, and so far this appears to work across a wide range of versions of MediaComposer and ProTools.
This is great if you need to pass information on for lasy minute edit changes for dubbing or if dubbing pick up on something that they need to pass back to you.
Locators from ProTools to MediaComposer