Sulfation and desulfation of cerebral cholecystokinin

An apparently novel sulfotransferase present in microsomal and vesicular fractions from rat brain is able to transfer [35S]sulfate groups from [35S]PAPS to CCK derivatives. Its optimum pH (approximately 6), its substrate specificity, and its subcellular localization are all consistent with its function as post-translational processing enzyme. However, its presence in tissues devoid of CCK argues against this idea, or could simply mean that it is involved in the processing of other peptides besides CCK. No evidence could be obtained for extensive desulfation of endogenous CCK-8 released by depolarization of brain slices.