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A specific histamine-stimulated phosphoprotein in isolated parietal cells
Abstract:
Histamine-stimulated phosphorylation was studied in isolated rabbit parietal cells. Secretion of acid, as assessed by aminopyrine uptake, was linear at 15 min of stimulation with histamine. By utilizing two dimensional gels, a specific 30,000-Da protein (pp30) was identified whose phosphorylation was prominently stimulated by histamine after 15 min of incubation. The pp30 protein displayed an isoelectric point of 6.0. Furthermore, cAMP-dependent pp30 phosphorylation could also be demonstrated in vitro in a preparation of parietal cell cytosol. The results suggest that pp30 may represent an important histamine-stimulated cAMP-dependent phosphoprotein involved in the initiation or maintenance of parietal cell secretion.
Insights
Histamine stimulates acid secretion in rabbit parietal cells by phosphorylating a 30,000-Da protein (pp30). This cAMP-dependent protein phosphorylation is crucial for initiating or maintaining gastric acid secretion.
Area of Science:
- Cell biology
- Gastroenterology
- Molecular biology
Background:
- Parietal cells are responsible for gastric acid secretion.
- Histamine is a key stimulant of acid secretion.
- The molecular mechanisms underlying histamine-stimulated acid secretion require further elucidation.
Purpose of the Study:
- To identify specific proteins involved in histamine-stimulated parietal cell secretion.
- To investigate the role of protein phosphorylation in this process.
- To characterize the properties of histamine-stimulated phosphoproteins.
Main Methods:
- Isolated rabbit parietal cells were used.
- Acid secretion was measured by aminopyrine uptake.
- Two-dimensional gel electrophoresis was employed to identify phosphoproteins.
- In vitro phosphorylation assays were performed on parietal cell cytosol.
Main Results:
- Histamine stimulation led to linear acid secretion after 15 minutes.
- A 30,000-Da protein (pp30) was identified, showing prominent histamine-stimulated phosphorylation.
- pp30 has an isoelectric point of 6.0.
- pp30 phosphorylation was demonstrated to be cAMP-dependent in vitro.
Conclusions:
- pp30 is a significant histamine-stimulated, cAMP-dependent phosphoprotein in parietal cells.
- pp30 likely plays a critical role in initiating or maintaining gastric acid secretion.
- Further research into pp30 function could reveal new therapeutic targets for acid-related disorders.