Abstract
Human placental Choline Acetyltransferase (ChAT) has been shown to be phosphorylated in vitro by kinases present in rat brain. Phosphorylation occurs at a single site with the exclusive phosphoamino acid being serine. ChAT phosphorylation was shown to be calcium, and not cyclic nucleotide, dependent and was inhibited by inhibitors of calcium/calmodulin protein kinases including anti-calmodulin anti-sera. ChAT phosphorylation was stimulated by calmodulin (9 fold) and, to a lesser extent, by phosphatidylserine (4 fold). These results indicate the involvement of a calcium/calmodulin and possibly also a calcium/phosopholipid kinase. This finding was confirmed by demonstrating ChAT phosphorylation using both purified multifunctional calcium/calmodulin protein kinase (CaMK) and calcium/phospholipid protein kinase C (PKC) from rat brain. A stoichiometric incorporation of 0.9 mol phosphate/mol ChAT was achieved by CaMK. Phosphorylated ChAT could be isolated from freshly prepared rat brain synaptosomes. The results obtained with this model system support the hypothesis that in vivo a fraction of ChAT exists phosphorylated.
| Original language | English |
|---|---|
| Pages (from-to) | 613-620 |
| Number of pages | 8 |
| Journal | Neurochemical Research |
| Volume | 14 |
| Issue number | 7 |
| DOIs | |
| State | Published - Jul 1989 |
Keywords
- Choline acetyltransferase
- phosphorylation
- protein kinase
- regulation
ASJC Scopus subject areas
- Biochemistry
- Cellular and Molecular Neuroscience