| First Author | Hosaka M | Year | 1998 |
| Journal | J Biol Chem | Volume | 273 |
| Issue | 3 | Pages | 1425-9 |
| PubMed ID | 9430678 | Mgi Jnum | J:45608 |
| Mgi Id | MGI:1195763 | Doi | 10.1074/jbc.273.3.1425 |
| Citation | Hosaka M, et al. (1998) Synapsins I and II are ATP-binding proteins with differential Ca2+ regulation. J Biol Chem 273(3):1425-9 |
| abstractText | Synapsins I and II are abundant phosphoproteins that are localized to synaptic vesicles and have essential functions in regulating synaptic vesicle exocytosis. Synapsins contain a single evolutionarily conserved, large central domain, the C-domain, that accounts for the majority of their sequences. Unexpectedly, the crystal structure of the C-domain from synapsin I revealed that it is structurally closely related to several ATPases despite the absence of sequence similarities (Esser, L., Wang, C.-R., Hosaka, M., Smagula, C. S., Sudhof, T. C., and Deisenhofer, J. (1998) EMBO J., in press). We now show that the C-domains of both synapsin I and synapsin II constitute high affinity ATP-binding modules. The two C-domains exhibit similar ATP affinities but are differentially regulated; ATP binding to synapsin I is Ca(2+)- dependent whereas ATP binding to synapsin II is Ca(2+)-independent. In synapsin I, the Ca2+ requirement for ATP binding is mediated by a single, evolutionarily conserved glutamate residue (Glu373) at a position where synapsin II contains a lysine residue. Exchange of Glu373 for lysine converts synapsin I from a Ca(2+)-dependent protein into a Ca(2+)-independent ATP-binding protein. Our studies suggest that synapsins I and II function on synaptic vesicles as ATP-binding proteins that are differentially regulated by Ca2+. |
