Related Experiment Videos
Immunolocalization of the sarcolemmal Ca2+/Mg2+ ecto-ATPase (myoglein) in rat myocardium
S Kannan1, V Elimban, R R Fandrich
1Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Winnipeg, Canada.
Abstract:
Cardiac plasma membrane Ca2+/Mg2+ ecto-ATPase (myoglein) requires millimolar concentrations of either Ca2+ or Mg2+ for maximal activity. In this paper, we report its localization by employing an antiserum raised against the purified rat cardiac Ca2+/Mg2+ ATPase. As assessed by Western blot analysis, the antiserum and the purified immunoglobulin were specific for Ca2+/Mg2+ ecto-ATPase; no cross reaction was observed towards other membrane bound enzymes such as cardiac sarcoplasmic reticulum Ca(2+)-pump ATPase or sarcolemmal Ca(2+)-pump ATPase. On the other hand, the cardiac Ca2+/Mg2+ ecto-ATPase was not recognized by antibodies specific for either cardiac sarcoplasmic reticulum Ca(2+)-pump ATPase or plasma membrane Ca(2+)-pump ATPase. Furthermore, the immune serum inhibited the Ca2+/Mg2+ ecto-ATPase activity of the purified enzyme preparation. Immunofluorescence of cardiac tissue sections and neonatal cultured cardiomyocytes with the Ca2+/Mg2+ ecto-ATPase antibodies indicated the localization of Ca2+/Mg2+ ecto-ATPase in association with the plasma membrane of myocytes, in areas of cell-matrix or cell-cell contact. Staining for the Ca2+/Mg2+ ecto-ATPase was not cardiac specific since the antibodies detected the presence of membrane proteins in sections from skeletal muscle, brain, liver and kidney. The results indicate that Ca2+/Mg2+ ecto-ATPase is localized to the plasma membranes of cardiomyocytes as well as other tissues such as brain, liver, kidney and skeletal muscle.
Insights
Cardiac plasma membrane Ca2+/Mg2+ ecto-ATPase (myoglein) is localized to the plasma membrane in cardiomyocytes and other tissues. This enzyme is crucial for cellular function and is not cardiac-specific, appearing in brain, liver, kidney, and skeletal muscle.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Cardiology
Background:
- Cardiac plasma membrane Ca2+/Mg2+ ecto-ATPase (myoglein) is an enzyme requiring high Ca2+ or Mg2+ concentrations for activity.
- Its precise cellular localization within cardiac tissue was previously uncharacterized.
Purpose of the Study:
- To determine the localization of cardiac plasma membrane Ca2+/Mg2+ ecto-ATPase in cardiac tissue.
- To investigate the specificity of antibodies against this ecto-ATPase.
Main Methods:
- Western blot analysis using a specific antiserum against purified rat cardiac Ca2+/Mg2+ ATPase.
- Immunofluorescence microscopy on cardiac tissue sections and cultured cardiomyocytes.
- Testing antibody specificity against other ATPases and cross-reactivity with non-cardiac tissues.
Main Results:
- The generated antiserum was specific for cardiac Ca2+/Mg2+ ecto-ATPase and inhibited its activity.
- Immunofluorescence localized the ecto-ATPase to the plasma membrane of cardiomyocytes, particularly at cell-matrix and cell-cell contact sites.
- The ecto-ATPase was also detected in skeletal muscle, brain, liver, and kidney, indicating it is not cardiac-specific.
Conclusions:
- Cardiac Ca2+/Mg2+ ecto-ATPase (myoglein) is localized to the plasma membrane of cardiomyocytes.
- This enzyme is also present in various other tissues, including brain, liver, kidney, and skeletal muscle.
- The findings provide insights into the distribution and potential roles of this ecto-ATPase in different cell types.