| First Author | Faundez VV | Year | 2000 |
| Journal | Mol Biol Cell | Volume | 11 |
| Issue | 8 | Pages | 2591-604 |
| PubMed ID | 10930456 | Mgi Jnum | J:120412 |
| Mgi Id | MGI:3706494 | Doi | 10.1091/mbc.11.8.2591 |
| Citation | Faundez VV, et al. (2000) The AP-3 complex required for endosomal synaptic vesicle biogenesis is associated with a casein kinase Ialpha-like isoform. Mol Biol Cell 11(8):2591-604 |
| abstractText | The formation of small vesicles is mediated by cytoplasmic coats the assembly of which is regulated by the activity of GTPases, kinases, and phosphatases. A heterotetrameric AP-3 adaptor complex has been implicated in the formation of synaptic vesicles from PC12 endosomes (). When the small GTPase ARF1 is prevented from hydrolyzing GTP, we can reconstitute AP-3 recruitment to synaptic vesicle membranes in an assembly reaction that requires temperatures above 15 degrees C and the presence of ATP suggesting that an enzymatic step is involved in the coat assembly. We have now found an enzymatic reaction, the phosphorylation of the AP-3 adaptor complex, that is linked with synaptic vesicle coating. Phosphorylation occurs in the beta3 subunit of the complex by a kinase similar to casein kinase 1alpha. The kinase copurifies with neuronal-specific AP-3. In vitro, purified casein kinase I selectively phosphorylates the beta3A and beta3B subunit at its hinge domain. Inhibiting the kinase hinders the recruitment of AP-3 to synaptic vesicles. The same inhibitors that prevent coat assembly in vitro also inhibit the formation of synaptic vesicles in PC12 cells. The data suggest, therefore, that the mechanism of AP-3-mediated vesiculation from neuroendocrine endosomes requires the phosphorylation of the adaptor complex at a step during or after AP-3 recruitment to membranes. |
