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Cation-activated phosphatase activities in islet cell plasma membrane preparations
Hormone and Metabolic Research. Supplement Series
|January 1, 1980
Summary
Researchers isolated rat and mouse pancreatic islet plasma membranes to study their enzymatic activities. They found ATP-dependent calcium binding, suggesting a role for ATP in islet cell function and cation transport.
Area of Science:
- Biochemistry
- Cell Biology
- Endocrinology
Background:
- Pancreatic islets are crucial for glucose homeostasis.
- Understanding islet plasma membrane function is key to metabolic research.
Purpose of the Study:
- To isolate and characterize plasma membranes from rat and ob/ob mouse pancreatic islets.
- To investigate enzymatic activities and ion binding properties of islet plasma membranes.
Main Methods:
- Sucrose gradient centrifugation for plasma membrane enrichment.
- Assays for Mg-ATP-gamma-3Pp hydrolysis and K+-activated phosphatase activity.
- Measurement of 45Ca2+ binding to islet plasma membranes.
Main Results:
- A plasma membrane-enriched fraction was successfully isolated.
- High specific activity of Mg-ATP-gamma-3Pp hydrolysis was observed, unaffected by K+/Na+.
- K+-activated, ouabain-sensitive phosphatase activities were demonstrated and inhibited by ATP.
- ATP increased 45Ca2+ binding to mouse islet plasma membranes.
Conclusions:
- Islet plasma membranes possess distinct enzymatic activities.
- ATP plays a role in regulating Ca2+ binding to islet plasma membranes.
- Phosphoryl-transfer reactions involving ATP may influence cation transport and Ca2+ interactions in islet cells.