Cabaniols J P, Ravichandran V, Roche P A
Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Mol Biol Cell. 1999 Dec;10(12):4033-41. doi: 10.1091/mbc.10.12.4033.
The docking and fusion of cargo-containing vesicles with target membranes of eukaryotic cells is mediated by the interaction of SNARE proteins present on both vesicle and target membranes. In many cases, the target membrane SNARE, or t-SNARE, exists as a complex of syntaxin with a member of the SNAP-25 family of palmitoylated proteins. We have identified a novel human kinase SNAK (SNARE kinase) that specifically phosphorylates the nonneuronal t-SNARE SNAP-23 in vivo. Interestingly, only SNAP-23 that is not assembled into t-SNARE complexes is phosphorylated by SNAK, and phosphorylated SNAP-23 resides exclusively in the cytosol. Coexpression with SNAK significantly enhances the stability of unassembled SNAP-23, and as a consequence, the assembly of newly synthesized SNAP-23 with syntaxin is augmented. These data demonstrate that phosphorylation of SNAP-23 by SNAK enhances the kinetics of t-SNARE assembly in vivo.
含货物的囊泡与真核细胞靶膜的对接和融合是由囊泡和靶膜上存在的SNARE蛋白相互作用介导的。在许多情况下，靶膜SNARE（或t-SNARE）以 syntaxin 与棕榈酰化的SNAP-25家族成员的复合物形式存在。我们鉴定出一种新型人类激酶SNAK（SNARE激酶），它在体内特异性磷酸化非神经元t-SNARE SNAP-23。有趣的是，只有未组装成t-SNARE复合物的SNAP-23被SNAK磷酸化，且磷酸化的SNAP-23仅存在于细胞质中。与SNAK共表达显著增强了未组装的SNAP-23的稳定性，因此，新合成的SNAP-23与syntaxin的组装增加。这些数据表明，SNAK介导的SNAP-23磷酸化增强了体内t-SNARE组装的动力学。
