Palmitoylation is the reversible addition of palmitate to cysteine via a thioester linkage. The reversible nature of this modification makes it a prime candidate as a mechanism for regulating signal transduction in T-cell receptor signaling. Following stimulation of the T-cell receptor we find a number of proteins are newly palmitoylated, including those involved in vesicle-mediated transport and Ras signal transduction. Among these stimulation-dependent palmitoylation targets are the v-SNARE VAMP7, important for docking of vesicular LAT during TCR signaling, and the largely undescribed palmitoyl acyltransferase DHHC18 that is expressed in two isoforms in T cells. Using our newly developed On-Plate Palmitoylation Assay (OPPA), we show DHHC18 is capable of palmitoylating VAMP7 at Cys183. Cellular imaging shows that the palmitoylation-deficient protein fails to be retained at the Golgi and to localize to the immune synapse upon T cell activation.

棕榈酰化是通过硫酯键将棕榈酸酯可逆地添加至半胱氨酸。这种修饰的可逆性使其成为调节T细胞受体信号转导机制的主要候选药物。刺激T细胞受体后，我们发现许多蛋白质被新棕榈酰化，包括那些与囊泡介导的转运和Ras信号转导有关的蛋白质。在这些依赖刺激的棕榈酰化靶标中，有v-SNARE VAMP7（对TCR信号传导期间囊泡LAT的对接很重要），以及在T细胞中以两种同工型表达的很大程度上未描述的棕榈酰酰基转移酶DHHC18。使用我们新开发的板上棕榈酸酯化测定法（OPPA），我们显示DHHC18能够在Cys183上棕榈酸酯化VAMP7。