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Characterization of type II activin receptors. Binding, processing, and phosphorylation
1Clayton Foundation Laboratories for Peptide Biology, Salk Institute, La Jolla, California 92037.
The Journal of Biological Chemistry
|September 5, 1993
Summary
Activin type II receptors are transmembrane protein kinases that bind activins. These receptors are phosphoproteins, with some phosphorylation sites arising from autophosphorylation, indicating complex signaling mechanisms.
Area of Science:
- Cell biology
- Molecular biology
- Biochemistry
Background:
- Activins are signaling molecules that bind to specific cell surface receptors.
- Two classes of activin receptors exist: type I (50-55 kDa) and type II (70-75 kDa).
Purpose of the Study:
- To characterize the properties of type II activin receptors in vivo.
- To investigate the post-translational modifications and phosphorylation status of type II activin receptors.
Main Methods:
- Immunoprecipitation using antibodies against cloned type II activin receptors.
- Chemical cross-linking of 125I-activin A to receptors.
- Treatment with peptide N-glycosidase F to analyze glycosylation.
- Metabolic labeling with [32P]orthophosphate to study phosphorylation.
- Analysis of tryptic phosphopeptide maps.
Main Results:
- Type II activin receptors are transmembrane protein serine kinases.
- Type I and type II receptors form complexes.
- Type II receptors possess N-linked carbohydrate chains.
- Type II receptors are phosphoproteins, primarily containing phosphoserine.
- Evidence suggests autophosphorylation contributes to receptor phosphorylation.
Conclusions:
- Type II activin receptors are complex transmembrane signaling proteins.
- Post-translational modifications like glycosylation and phosphorylation are crucial for their function.
- Autophosphorylation plays a role in the signaling of activin receptors.