Calmodulin activation of plant microsomal Ca 2+ uptake

Abstract

The active ATP-dependent uptake of Ca2+ into a plasma membrane-enriched microsomal fraction from plants is stimulated by the addition of plant and bovine brain calmodulin. This stimulation occurs only when the microsomes are prepared in the presence of EDTA. Plant calmoculin from zucchini activates the bovine brain 3'',5''-cyclic-nucleotide phosphodiesterase (EC 3.1.4.17). Mitochondrial Ca2+ accumulation is not affected by calmodulin. The calmodulin-mediated activation of microsomal Ca2+ uptake is abolished by the antipsychotic drug fluphenazine; the calmodulin-independent Ca2+ uptake is only slightly decreased.