The C‐terminal HDEL sequence is sufficient for retention of secretory proteins in the endoplasmic reticulum (ER) but promotes vacuolar targeting of proteins that escape the ER

作者：Véronique Gomord, Lise‐Anne Denmat, Anne‐Catherine Fitchette‐Lainé, Béatrice Satiat‐Jeunemaître, Chris R. Hawes, Loic J-Y Faye · 发表于：The Plant Journal · 年份：1997 · DOI：10.1046/j.1365-313x.1997.11020313.x · 被引用次数：227 · 研究领域：Transgenic Plants and Applications、Endoplasmic Reticulum Stress and Disease、Plant tissue culture and regeneration

Proteins are co-translationally transferred into the endoplasmic reticulum (ER) and then either retained or transported to different intracellular compartments or to the extracellular space. Various molecular signals necessary for retention in the ER or targeting to different compartments have been identified. In particular, the HDEL and KDEL signals used for retention of proteins in yeast and animal ER have also been described at the C-terminal end of soluble ER processing enzymes in plants. The fusion of a KDEL extension to vacuolar proteins is sufficient for their retention in the ER of transgenic plant cells. However, recent results obtained using the same strategy indicate that HDEL does not contain sufficient information for full retention of phaseolin expressed in tobacco. In the present study, an HDEL C-terminal extension was fused to the vacuolar or extracellular (delta pro) forms of sporamin. The resulting SpoHDEL or delta proHDEL, as well as Spo and delta pro, were expressed at high levels in transgenic tobacco cells (Nicotiana tabacum cv BY2). The intracellular location of these different forms of recombinant sporamin was studied by subcellular fractionation. The results clearly indicate that addition of an HDEL extension to either Spo or delta pro induces accumulation of these sporamin forms in a compartment that co-purifies with the ER markers NADH cytochrome C reductase, binding protein (BiP) and calnexin. In addition, a significant SpoHDEL or delta proHDEL fra...