Title : Glycosylation
sites flank phosphorylation
sites on
synapsin I : O-linked N-acetylglucosamine residues are localized within
domains mediating
synapsin I interactions
Abstract :
- Synapsin I is concentrated in nerve terminals, where it appears to anchor synaptic vesicles to the cytoskeleton and thereby ensures a steady supply of fusion-competent synaptic vesicles
- Although phosphorylation-dependent binding of synapsin I to cytoskeletal elements and synaptic vesicles is well characterized, little is known about synapsin I 's O-linked N-acetylglucosamine (O-GlcNAc) modifications
- Here, we identified seven in vivo O-GlcNAcylation sites on synapsin I by analysis of HPLC-purified digests of rat brain synapsin I
- The seven O-GlcNAcylation sites ( Ser55, Thr56, Thr87, Ser516, Thr524, Thr562, and Ser576 ) in synapsin I are clustered around its five phosphorylation sites in domains B and D
- The proximity of phosphorylation sites to O-GlcNAcylation sites in the regulatory domains of synapsin I suggests that O-GlcNAcylation may modulate phosphorylation and indirectly affect synapsin I interactions
- With use of synthetic peptides , however, the presence of an O-GlcNAc at sites Thr562 and Ser576 resulted in only a 66% increase in the Km of calcium/calmodulin-dependent protein kinase II phosphorylation of site Ser566 with no effect on its Vmax
- We conclude that O-GlcNAcylation likely plays a more direct role in synapsin I interactions than simply modulating the protein's phosphorylation
Output (sent_index, trigger,
protein,
sugar,
site):
- 0. localized, , -, O-linked N-acetylglucosamine residues, domains
- 3. sites, , synapsin I, sites, -
- 4. sites, , synapsin I, sites, -
- 5. sites, , -, the regulatory domains, domains
- 5. sites, , synapsin I, sites, -
- 6. presence, , -, an O-GlcNAc, sites Thr562 and Ser576
Output(Part-Of) (sent_index,
protein,
site):
*Output_Site_Fusion* (sent_index,
protein,
sugar,
site):
- 6. synapsin I, an O-GlcNAc, sites Thr562 and Ser576