MICROSCOPIC LOCALIZATION OF ADENYLATE-CYCLASE - A HISTORICAL REVIEW OF METHODOLOGIES

The histochemistry technique for localizing adenylate cyclase has been developed over the past two decades. Early efforts were directed at o vercoming the criticism of the lead capture technique, the inhibition of the enzyme by fixation, and problems associated with the substrate. The introduction of alternative metal ions, strontium and cerium, off ered solutions to the criticism of the lead capture technique. The inh ibition of the enzyme by the various fixation methods used has been ra rely overcome satisfactorily and the use of non-fixed material during incubation is one of the alternatives that has been suggested. The int roduction of adenylate (beta-gamma-methylene) diphosphate as an altern ative substrate offers a solution to the problems associated with comm ercially available adenylyl imidodiphosphate. Although no standard med ium or method has been accepted by all researchers, the histochemical technique still has a place in the arsenal of the modern cell biologis t. The technique localizes the active enzyme, as opposed to the protei n, active and nonactive, by immunocytochemistry and the precursors of the protein by in situ hybridization methods. (C) 1998 Wiley-Liss, Inc .