Structural features of the surface of the vesicles of FSR—Lack of functional role in Ca2+ uptake and ATPase activity
| Autor: | Noriaki Ikemoto, J. Gergely, Frank A. Sreter |
|---|---|
| Rok vydání: | 1971 |
| Předmět: |
Calcium Isotopes
Sucrose Brush border Biophysics chemistry.chemical_element Uranyl acetate Calcium Biochemistry chemistry.chemical_compound Adenosine Triphosphate medicine Animals Trypsin Molecular Biology Adenosine Triphosphatases Oxalates Membranes Chemistry Muscles Endoplasmic reticulum Vesicle Phosphorus Isotopes Negative stain Enzyme Activation Kinetics Microscopy Electron Sarcoplasmic Reticulum Membrane Rabbits medicine.drug |
| Zdroj: | Archives of Biochemistry and Biophysics. 147:571-582 |
| ISSN: | 0003-9861 |
| Popis: | Negative staining with uranyl acetate of the vesicles of fragmented sarcoplasmic reticulum from rabbit skeletal muscle has revealed three structural components in the vesicle wall: (1) the membrane portion proper, (2) spheres with a diameter of about 40 A on the exterior surface of the vesicle membrane, and (3) stalks with a width of about 20 A connecting the spheres with the membrane. Digestion with trypsin (at a 1:20 trypsin-vesicle protein ratio by weight) in a medium containing 0.1 m KCl (pH 7.0) with or without added sucrose leads to the removal of both surface spheres and stalks leaving smooth vesicles. If 4 n m calcium is included during digestion, only the surface spheres disappear and vesicles attached to the exterior surface by what appears to be a brush border result. The previously reported loss of Ca 2+ uptake and increase in ATPase activity of vesicles during tryptic digestion are prevented by adding high concentrations of sucrose (1.0 m ) but not the removal of spheres and stalks. The capacity of forming the phosphorylated intermediate by the transport enzyme from ATP remains intact in these vesicles. Similarly, vesicles devoid of only the surface spheres obtained by digestion in the joint presence of sucrose and calcium have retained essentially intact activities. The results indicate that all important activities related to the Ca 2+ transport mechanism are located in the membrane portion proper of the vesicle wall, and that the surface spheres and stalks have little or no role to play in Ca 2+ transport. |
| Databáze: | OpenAIRE |
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