Characterization of transport of calcium by microsomal membranes from roots maize

Thesis/Dissertation · Tue Jan 01 00:00:00 EST 1985

OSTI ID:5021474

Vaughan, M A

This study investigates calcium transport by membranes of roots of maize isolated by differential centrifugation. The preparation was determined to be enriched in plasma membrane using market enzyme and electron microscopy. Using the /sup 45/Ca filtration technique and liquid scintillation counting, vesicular calcium uptake was shown to be stimulated by added calmodulin and specific for and dependent on ATP. Conditions for maximal calcium accumulation were found to be 30 min incubation in the presence of 5 mM ATP, 5 mM MgCl/sub 2/, 50 ..mu..M CaCl/sub 2/, at 23/sup 0/C, and at pH 6.5. Calcium uptake was inhibited by the ionophores A23187, X-537A, and ionomycin. Sodium fluoride, ruthenium red, and p-chloromercuribenzoate completely inhibited transport: diamide and vanadate produced slight inhibition; caffeine, caffeic acid, oligomycin, and ouabain produced little or no inhibition. Chlorpromazine, W7, trifluoperazine, and R 24 571 inhibit calcium uptake irrespective of added calmodulin, while W5 showed little effect on uptake. Verapamil, nifedipine, cinnarizine, flunarizine, lidoflazine, and diltiazem decreased calcium uptake by 17%-50%. Electron microscopic localization of calcium by pyroantimonate showed vesicles incubated with calmodulin and ATP showed the greatest amount of precipitate. These results suggest that these vesicles accumulate calcium in an ATP-dependent, calmodulin-stimulated manner.

• Research Organization: Indiana State Univ., Terre Haute (USA)
• OSTI ID: 5021474
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CALCIUM 45
BIOLOGICAL ACCUMULATION
RADIONUCLIDE KINETICS
UPTAKE
ATP
CELL MEMBRANES
MAIZE
ROOTS
ALKALINE EARTH ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CALCIUM ISOTOPES
CELL CONSTITUENTS
CEREALS
DAYS LIVING RADIOISOTOPES
EVEN-ODD NUCLEI
GRASS
INTERMEDIATE MASS NUCLEI
ISOTOPES
MEMBRANES
NUCLEI
NUCLEOTIDES
ORGANIC COMPOUNDS
PLANTS
RADIOISOTOPES
550201* - Biochemistry- Tracer Techniques