Further characterization of the red beet plasma membrane Ca 2+ -ATPase using GTP as an alternative substrate

Lorraine E. Williams, Sherry B. Schueler, Donald P Briskin

Research output: Contribution to journalArticle

Abstract

The GTP-driven component of Ca 2+ uptake in red beet (Beta vulgaris L) plasma membrane vesicles was further characterized to confirm its association with the plasma membrane Ca 2+ -translocating ATPase and assess its utility as a probe for this transport system. Uptake of 45 Ca 2+ in the presence of GTP demonstrated similar properties to those previously observed for red beet plasma membrane vesicles utilizing ATP with respect to pH optimum, sensitivity to orthovanadate, dependence on Mg:substrate concentration and dependence on Ca 2+ concentration. Calcium uptake in the presence of GTP was also strongly inhibited by erythrosin B, a potent inhibitor of the plant plasma membrane Ca 2+ -ATPase. Furthermore, after treatment with EGTA to remove endogenous calmodulin, the stimulation of 45 Ca 2+ -uptake by exogenous calmodulin was nearly equivalent in the presence of either ATP or GTP. Taken together these results support the proposal that GTP-driven 45 Ca 2+ uptake represents the capacity of the plasma membrane Ca 2+ -translocating ATPase to utilize this nucleoside triphosphate as an alternative substrate. When plasma membrane vesicles were phosphorylated with [γ- 32 P]-GTP, a rapidly turning over, 100 kilodalton phosphorylated peptide was observed which contained an acyl-phosphate linkage. While it is proposed that this peptide could represent the catalytic subunit of the plasma membrane Ca 2+ -ATPase, it is noted that this molecular weight is considerably lower than the 140 kilodalton size generally observed for plasma membrane Ca 2+ -ATPases present in animal cells.

Original languageEnglish (US)
Pages (from-to)747-754
Number of pages8
JournalPlant physiology
Volume92
Issue number3
DOIs
StatePublished - Mar 1990

Fingerprint

Beta vulgaris
beets
Guanosine Triphosphate
adenosinetriphosphatase
Adenosine Triphosphatases
plasma membrane
Cell Membrane
uptake mechanisms
calmodulin
Calmodulin
Adenosine Triphosphate
Erythrosine
peptides
erythrosine
Peptides
Vanadates
nucleosides
Egtazic Acid
protein subunits
Nucleosides

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science

Cite this

Further characterization of the red beet plasma membrane Ca 2+ -ATPase using GTP as an alternative substrate . / Williams, Lorraine E.; Schueler, Sherry B.; Briskin, Donald P.

In: Plant physiology, Vol. 92, No. 3, 03.1990, p. 747-754.

Research output: Contribution to journalArticle

Williams, Lorraine E. ; Schueler, Sherry B. ; Briskin, Donald P. / Further characterization of the red beet plasma membrane Ca 2+ -ATPase using GTP as an alternative substrate In: Plant physiology. 1990 ; Vol. 92, No. 3. pp. 747-754.
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