Stop App Store from updating?

I have an application on my computer that I don't want to update for a variety of reasons, but it causes the app store to continuously remind me of available updates. Is there a file I can delete (somewhere in the Package Contents or the "Hidden" Library, maybe?) that will stop the App Store from looking for updates? If it helps, the application is old enough that it was out when Software Update was still used to update apps instead of the App Store.