Controlled Proteolysis Activates the Plasma Membrane Ca2+ Pump of Higher Plants (A Comparison with the Effect of Calmodulin in Plasma Membrane from Radish Seedlings).
AUTOR(ES)
Rasi-Caldogno, F.
RESUMO
The effects of calmodulin and of controlled trypsin treatments on the activity of the Ca2+ pump were investigated in plasma membrane purified from radish (Raphanus sativus L.) seedlings. Treatment of the plasma membrane with ethylenediaminetetra-acetate (EDTA), which removed about two-thirds of the plasma membrane-associated calmodulin, markedly increased the stimulation of the Ca2+ pump by calmodulin. In EDTA-treated plasma membrane, stimulation by calmodulin of the Ca2+ pump activity was maximal at low free Ca2+ (2-5 [mu]M) and decreased with the increase of free Ca2+ concentration. The Ca2+ pump activity was stimulated also by a controlled treatment of the plasma membrane with trypsin: the effect of trypsin treatment depended on the concentration of both trypsin and plasma membrane proteins and on the duration of incubation. Stimulation of the Ca2+ pump activity by trypsin treatment of the plasma membrane was similar to that induced by calmodulin both in extent and in dependence on the free Ca2+ concentration in the assay medium. Moreover, the Ca2+ pump of trypsin-treated plasma membrane was insensitive to further stimulation by calmodulin, suggesting that limited proteolysis preferentially cleaves a regulatory domain of the enzyme that is involved in its activation by calmodulin.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=158994Documentos Relacionados
- Purification of the Plasma Membrane Ca2+-ATPase from Radish Seedlings by Calmodulin-Agarose Affinity Chromatography1
- Ca2+-Dependent, Stimulus-Specific Modulation of the Plasma Membrane Ca2+ Pump in Hippocampal Neurons
- Orai1, a critical component of store-operated Ca2+ entry, is functionally associated with Na+/Ca2+ exchanger and plasma membrane Ca2+ pump in proliferating human arterial myocytes
- A plant plasma membrane Ca2+ pump is required for normal pollen tube growth and fertilization
- A C-terminal, calmodulin-like regulatory domain from the plasma membrane Ca2+-pumping ATPase.
