Calcium homeostasis in barley aleurone
Under the auspices of the Department of Energy we investigated calcium homeostasis in aleurone cells of barley. This investigation was initiated to explore the role played by extracellular Ca{sup 2+} in gibberellic acid (GA)-induced synthesis and secretion of hydrolases in the aleurone layer. We have focused our attention on four topics that relate to the role of Ca{sup 2+} in regulating the synthesis of {alpha}-amylase. First, we determined the stoichiometry of Ca{sup 2+} binding to the two principal classes of barley {alpha}-amylase and examined some of the biochemical and physical properties of the native and Ca{sup 2+}-depleted forms of the enzyme. Second, since {alpha}-amylase is a Ca{sup 2+} containing metalloenzyme that binds one atom of Ca{sup 2+} per molecule, we developed methods to determine the concentration of Ca{sup 2+} in the cytosol of the aleurone cell. We developed a technique for introducing Ca{sup 2+}-sensitive dyes into aleurone protoplasts that allows the measurement of Ca{sup 2+} in both cytosol and endoplasmic reticulum (ER). Third, because the results of our Ca{sup 2+} measurements showed higher levels of Ca{sup 2+} in the ER than in the cytosol, we examined Ca{sup 2+} transport into the ER of control and GA-treated aleurone tissue. And fourth, we applied the technique of patch-clamping to the barley aleurone protoplast to examine ion transport at the plasma membrane. Our results with the patch-clamp technique established the presence of K{sup +} channels in the plasma membrane of the aleurone protoplast, and they showed that this cell is ideally suited for the application of this methodology for studying ion transport. 34 refs.
- Research Organization:
- California Univ., Berkeley, CA (USA)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (USA)
- DOE Contract Number:
- FG03-88ER13926
- OSTI ID:
- 5871431
- Report Number(s):
- DOE/ER/13926-T2; ON: DE91009840
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AMYLASE
BIOSYNTHESIS
BARLEY
HOMEOSTASIS
CALCIUM IONS
MEMBRANE TRANSPORT
STOICHIOMETRY
CALCIUM 45
CELL WALL
CYTOPLASM
DYES
ELECTROPHYSIOLOGY
ENDOPLASMIC RETICULUM
FLUORESCENCE
GENE REGULATION
GIBBERELLIC ACID
HORMONES
INDICATORS
ISOENZYMES
MICROSOMES
PLANT CELLS
POTASSIUM IONS
PROGRESS REPORT
SUBCELLULAR DISTRIBUTION
ALKALINE EARTH ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CALCIUM ISOTOPES
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CEREALS
CHARGED PARTICLES
DAYS LIVING RADIOISOTOPES
DISTRIBUTION
DOCUMENT TYPES
ENZYMES
ESTERS
EVEN-ODD NUCLEI
GLYCOSYL HYDROLASES
GRASS
HETEROCYCLIC COMPOUNDS
HYDROLASES
HYDROXY ACIDS
INTERMEDIATE MASS NUCLEI
IONS
ISOTOPES
LACTONES
LILIOPSIDA
LUMINESCENCE
MAGNOLIOPHYTA
NUCLEI
O-GLYCOSYL HYDROLASES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANOIDS
PHYSIOLOGY
PLANTS
RADIOISOTOPES
RIBOSOMES
SYNTHESIS
550201* - Biochemistry- Tracer Techniques
551001 - Physiological Systems- Tracer Techniques
550301 - Cytology- Tracer Techniques