title: Affinity of heavy metal ions to intracellular Ca2+-binding proteins.
abstract: Parvalbumin, troponin C and vitamin D dependent Ca2+-binding proteins (CaBP type I and II) share the property of calmodulin to interact with some heavy metal ions. In flow dialysis and in spot tests the affinities of Cd2+ and Pb2+ to these proteins were comparable to those of Ca2+. The relative affinities were for calmodulin: Pb2+ greater than Ca2+ greater than Cd2+, for troponin C: Ca2+ greater than Cd2+ greater than Pb2+, for CaBP I: Ca2+ approximately Pb2+, for CaBP II; Ca2+ greater than Pb2+ greater than Cd2+, and for parvalbumin: Cd2+ approximately Ca2+ greater than Pb2+. Upon gel filtration of the supernatant of a pig mucosal homogenate, binding for both Pb2+ and Ca2+ appeared in the MW range of 10,000, together with CaBP II. We conclude that the investigated proteins bind heavy metal ions, in particular Pb2+ and Cd2+, similar to calmodulin. Their role in transport, storage and toxicity remains to be assessed.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002104:Cadmium / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000378:metabolism; D007854:Lead / Q000378:metabolism; D008670:Metals / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D013552:Swine
chemical_list: D002135:Calcium-Binding Proteins; D002147:Calmodulin; D008670:Metals; D064030:S100 Calcium Binding Protein G; D002104:Cadmium; D007854:Lead; D002118:Calcium