Abstract
Insulin secretion from pancreatic β-cells has to be tightly regulated to ensure accurate glucose homeostasis. The capacity of β-cells to respond to extracellular stimulation is determined by several signaling pathways. One important feature of these pathways is phosphorylation and subsequent dephosphorylation of a wide range of cellular substrates. Protein phosphatase 1 (PP1) is a major eukaryotic serine/threonine protein phosphatase that controls a multitude of physiological processes. We have investigated the expression and cellular distribution of two endogenous inhibitors of PP1 activity in β-cells. RT-PCR, Western blotting, and immunohistochemistry showed that DARPP-32 and inhibitor-1 are present in insulin-secreting endocrine β-cells. Subcellular fractionation of mouse islets revealed that both PP1 inhibitors predominantly localized to cytosol-enriched fractions. Inhibitor-1 was also present in fractions containing plasma membrane-associated proteins. These data indicate a potential role for DARPP-32 and inhibitor-1 in the regulation of PP1 activity in pancreatic β-cell stimulus-secretion coupling.
Original language | English (US) |
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Pages (from-to) | 673-677 |
Number of pages | 5 |
Journal | Biochemical and biophysical research communications |
Volume | 329 |
Issue number | 2 |
DOIs | |
State | Published - Apr 8 2005 |
Keywords
- Dephosphorylation
- Exocytosis
- Immunohistochemistry
- Insulin
- Phosphatase
- PP1 inhibitor
- RT-PCR
- Secretion
- Subcellular fractionation
ASJC Scopus subject areas
- Biochemistry
- Biophysics
- Molecular Biology