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A Ca2+-dependent protein kinase activity associated with serotonin binding protein
Journal of Neurochemistry
|October 1, 1987
Summary
Phosphorylation of serotonin binding protein (SBP) by SBP-kinase inhibits serotonin binding. SBP-kinase is distinct from CAM-PK II, suggesting SBP phosphorylation regulates serotonin transport in neurons.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Serotonin binding protein (SBP) plays a role in serotonergic neurons.
- Endogenous phosphorylation of SBP inhibits serotonin (5-HT) binding.
Purpose of the Study:
- To characterize SBP-kinase activity.
- To compare SBP-kinase with calcium/calmodulin-dependent protein kinase II (CAM-PK II).
- To investigate the role of SBP phosphorylation in serotonin transport.
Main Methods:
- Partial characterization of SBP-kinase.
- Comparison of SBP-kinase and CAM-PK II using various substrates and activators.
- Analysis of phosphopeptide maps.
Main Results:
- SBP-kinase shares some characteristics with CAM-PK II, including subunit size and Ca2+-dependent autophosphorylation.
- SBP-kinase and CAM-PK II differ in their response to calmodulin, substrate specificity (synapsin I), and regulation by serotonin.
- Serotonin inhibited SBP-kinase activity and SBP phosphorylation but not CAM-PK II.
Conclusions:
- SBP-kinase is a distinct molecular entity, different from CAM-PK II.
- Phosphorylation of SBP by SBP-kinase may regulate serotonin transport within neurons.