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Spectrin phosphorylation in senescent rat erythrocytes
Mechanisms of Ageing and Development
|May 1, 1983
Summary
Phosphorylation of spectrin, an erythrocyte protein, decreases with age due to structural changes in spectrin itself. This age-related spectrin alteration impairs its function as a protein kinase substrate.
Area of Science:
- Biochemistry
- Cell Biology
- Gerontology
Background:
- Erythrocyte (red blood cell) aging involves changes in protein function.
- Spectrin is a key cytoskeletal protein in erythrocytes, crucial for maintaining cell shape and integrity.
- Phosphorylation is a critical post-translational modification regulating protein function.
Purpose of the Study:
- To investigate the age-dependent changes in spectrin phosphorylation in rat erythrocytes.
- To determine whether decreased phosphorylation is due to altered kinase/phosphatase activity or changes in spectrin structure.
- To explore the structural basis for impaired spectrin phosphorylation in aged erythrocytes.
Main Methods:
- Age-separated young and old rat erythrocytes were used.
- Endogenous membrane protein kinase and phosphatase activities were measured.
- Partially purified spectrin kinase and spectrin from young and old erythrocytes were prepared.
- Phosphorylation of spectrin by isolated kinases was quantified.
- Erythrocyte membranes were treated with malonyldialdehyde to assess its effect on spectrin phosphorylation.
Main Results:
- Protein kinase activity in erythrocyte membranes decreased with cell age.
- Spectrin phosphatase activity remained comparable between young and old erythrocytes.
- Kinases from young or old cells phosphorylated spectrin from young cells equally.
- Spectrin from old cells was phosphorylated 10-fold less by kinase from old cells compared to kinase from young cells.
- Malonyldialdehyde treatment impaired spectrin phosphorylation, suggesting lipid peroxidation's role.
Conclusions:
- Decreased spectrin phosphorylation in aged erythrocytes is primarily due to a structural alteration within the spectrin molecule itself.
- Intramolecular derivatization of spectrin, potentially from lipid peroxidation products like malonyldialdehyde, impairs its ability to be phosphorylated.
- These findings highlight a structural basis for age-related decline in spectrin function within erythrocytes.