Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Enyedi, A; Sarkadi, B; Földes-Papp, Z; Monostory, S; Gárdos, G.
Demonstration of two distinct calcium pumps in human platelet membrane vesicles.
J Biol Chem. 1986; 261(20): 9558-9563.
Doi: 10.1016/S0021-9258(18)67694-X
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- Földes-Papp Zeno
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- Abstract:
- Membrane vesicles from human platelets were prepared by various disruption and isolation techniques reported in the literature to yield fractions of predominantly surface or intracellular membrane origin. ATP + Mg2+-dependent Ca2+ accumulation and the formation of acylphosphate intermediates of the calcium pump(s) were followed in parallel experiments, and the consequences of a limited proteolysis of the membranes examined. In all types of preparations active Ca2+ uptake had both oxalate-sensitive and insensitive fractions and calmodulin had no effect on the rate of Ca2+ uptake. Limited proteolysis by trypsin eliminated oxalate-sensitive Ca2+ uptake while it had no effect on the oxalate-insensitive fraction. The Ca2+-induced EP complex had an apparent molecular mass of 100-110 kDa in all of the preparations, the EP showing a broad or even duplicated line in most autoradiographies. Mild trypsin digestion resulted in the formation of 80-, 55-, and 35-kDa phosphorylated fragments. The 80-kDa fragment corresponded to the limit polypeptide found in the proteolyzed erythrocyte membrane Ca2+ pump, its phosphorylation was stimulated by lanthanum, and it appeared in a different time course than the smaller fragments. The molecular mass and the formation pattern of the latter species corresponded to the tryptic fragments in the sarcoplasmic reticulum Ca2+ pump. Based on these results we suggest that platelet membrane preparations contain two types of Ca2+ pump proteins, one similar to the sarcoplasmic reticulum-type and the other to the erythrocyte-type enzyme.
- Find related publications in this database (using NLM MeSH Indexing)
- Adenosine Triphosphatases - blood
- Adenosine Triphosphate - pharmacology
- Blood Platelets - metabolism
- Calcium - blood
- Cell Membrane - metabolism
- Humans - metabolism
- Ion Channels - drug effects
- Lanthanum - pharmacology
- Magnesium - pharmacology
- Microscopy, Electron - pharmacology
- Oxalates - pharmacology
- Oxalic Acid - pharmacology
- Phosphates - blood
- Trypsin - pharmacology