Occluded cations in active transport.

INTRODUCTION . .. , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 7 1 OCCLUSION I N PUMPS OTHER THAN P-TYPE ATPases 1 73 Redox Pumps . . .... . . .... . .. . . . .. . . . . .. . . ... . . . .. . . . ... , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... . . . . . . 1 73 Light-Driven Pumps 1 74 F IF 0 ATPases 1 74 OCCLUSION IN P-TYPE A TPases 175 Sarcoplasmic Ca-ATPase 1 75 Na,K-ATPases . 1 80 THE CHEMICAL NATURE OF OCCLUSION SITES . ... . . . .. ........ ... . . . . .... . .... . . . . 1 88 Cation-Binding Sites in Proteins and lonophores . . . . . . . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . 1 88 Cations as Probes of Sites ...... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 Chemical Labelling and Site-Directed Mutagenesis 192 Charge Transfer 197 CONCLUSION . . ..... . .... . ........ 200