The biggest of which is Luxury Suites International (LSI). There are three other management companies that also manage suites there, Jet Luxury Suites, Las Vegas Suites (formally known as Blue Chip Management), Luxury Suite International and Linda Corbridge (also known as By Owner's Direct). Should the owner choose to allow MGM to rent out their suite then it is rented as part of 'The Signature at MGM Grand' hotel. All of the suites are individually owned. It is the condo/hotel project for MGM Grand similar to the Vadara and Trump International.
I've worked at The Signature and would be happy to answer any questions that you might have on that property.