Apparently not. For instance the flagellum is classified either in terms of proteins or three larger units ("motor", "hook" and "whip" IIRC). Behe wasn't clear in his book, and readers tended to assume that he meant proteins. Dembski's worthless probability calculation was also protein-based. Yet Behe insists that he meant the larger units.
And that isn't the end of the problems with that definition.
A system performing a given basic function is irreducibly complex if it includes a set of well-matched, mutually interacting, nonarbitrarily individuated parts such that each part in the set is indispensable to maintaining the system's basic, and therefore original, function. The set of these indispensable parts is known as the irreducible core of the system
The bolded clause was inserted to rule out explanations involving a change of function by fiat. Which is cheating.
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