Allosteric inhibitors of plasma membrane Ca2+ pumps: Invention and applications of caloxins

Figure 1 Extracellular domains (exdoms) in human plasma membrane Ca²⁺ pump protein. Sequences of exdom 1 of human plasma membrane Ca²⁺ pump protein (PMCA)1 to 4 are also compared (Swiss protein bank accession #P20020, Q01814, Q16720, P23634). Exdom 1 is long and contains a C in the middle. It was divided into two segments: exdoms 1X and 1Y around the C.

Figure 2 Caloxin 2A1 inhibition of plasma membrane Ca²⁺ pump ATPase in the erythrocyte ghosts is non-competitive with respect to Ca²⁺, ATP and calmodulin[22]. The percent inhibition with caloxin 2a1 (1.8 mmol/L) did not differ significantly between low or high concentration of Ca²⁺. Similarly, concentrations of ATP and calmodulin did not influence the percent inhibition with caloxin 2a1. The low and high concentrations compared for each ligand are shown. Concentrations of all the other ligands were saturating in each experiment. Details of the experiments are available in[22].