We show that each of the three K-theory multifunctors from small permutative categories to G * -categories, G * -simplicial sets, and connective spectra, is an equivalence of homotopy theories. For each of these K-theory multifunctors, we describe an explicit homotopy inverse functor. As a separate application of our general results about pointed diagram categories, we observe that the rightinduced homotopy theory of Bohmann-Osorno E * -categories is equivalent to the homotopy theory of pointed simplicial categories.