Calcium transport by macrophage plasma membranes.

Macrophage Plasma Membranes

Plasma membranes have been isolated from pure populations of rabbit alveolar macrophages which were swollen in water, fixed briefly with glutaraldehyde, disrupted by Dounce homogenization, and separated by sucrose gradient centrifugation. The recovered membranes exhibited good structural preservation and enzymatic activity; both morphologic and biochemical evidence indicated a high degree of pu...

Inositol 1,4,5-trisphosphate-gated calcium transport through plasma membranes in nerve terminals.

We developed new biochemical approaches to demonstrate the presence of inositol 1,4,5-triphosphate (InsP3)-gated calcium channels in presynaptic plasma membranes (SPM) and their involvement in the presynaptic receptor-mediated Ca2+ influx into nerve terminals. In perfusion experiments using SPM vesicles preloaded with 45Ca2+, InsP3 elicited the release of 45CA2+ into perfusates in a saturable m...

Transmembrane Electron Transport Systems in Erythrocyte Plasma Membranes

Calmodulin-regulated, ATP-driven calcium transport by basolateral membranes of rat small intestine.

Uptake of calcium by a membrane fraction enriched in basolateral plasma membrane vesicles from rat small intestine has been investigated using a rapid filtration technique. Calcium accumulation is stimulated by ATP and released by the calcium ionophore A23187. Kinetic studies indicate a calcium concentration of 28 nM for half-maximal stimulation of ATP-driven uptake. Transport is minimally inhi...

Inhibition by glucagon of the calcium pump in liver plasma membranes.

The ATP-dependent calcium transport in plasma membrane vesicles prepared from rat liver was inhibited by 0.1 to 10 microM glucagon. Inhibition of the high affinity (Ca2+-Mg2+)-ATPase was observed concomitantly. This effect was neither mimicked by cyclic AMP nor by dibutyryl cyclic AMP. A study of the structure-activity relationships of six glucagon derivatives demonstrated the specificity of gl...