期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2004
卷号：101
期号：14
页码：4815-4820
DOI：10.1073/pnas.0401183101
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) catalyze compartment-specific membrane fusion. Whereas most SNAREs are bona fide type II membrane proteins, Ykt6 lacks a proteinaceous membrane anchor but contains a prenylation consensus motif (CAAX box) and exists in an inactive cytosolic and an active membrane-bound form. We demonstrate that both forms are farnesylated at the carboxyl-terminal cysteine of the CCAIM sequence. Farnesylation is the prerequisite for subsequent palmitoylation of the upstream cysteine, which permits stable membrane association of Ykt6. The double-lipid modification and membrane association is crucial for intra-Golgi transport in vitro and cell homeostasis/survival in vivo. The membrane recruitment and palmitoylation is controlled by the N-terminal domain of Ykt6, which interacts with the SNARE motif, keeping it in an inactive closed conformation. Together, these results suggest that conformational changes control the lipid modification and function of Ykt6. Considering the essential and central role of Ykt6 in the secretory pathway, this spatial and functional cycle might provide a mechanism to regulate the rate of intracellular membrane flow.
