Mancone Carmine, Amicone Laura, Fimia Gian Maria, Bravo Elena, Piacentini Mauro, Tripodi Marco, Alonzi Tonino
National Institute for Infectious Diseases L. Spallanzani, IRCCS, Rome, Italy.
Proteomics. 2007 Jan;7(1):143-54. doi: 10.1002/pmic.200600339.
Biochemical studies of lipoproteins have shed light on their composition, highly contributing to the comprehension of their function. Due to the complexity of their structure, however, an in-depth structural analysis, in terms of components and PTMs, may still unravel important players in physiological and pathological processes of lipid metabolism. In this study, we performed a protein map of very low-density lipoprotein (VLDL) using a 2-DE MALDI-TOF/TOF proteomic approach. Several VLDL-associated apolipoproteins were identified, including five isoforms of apoE, three isoforms of apoC-IV, and one isoform each of apoC-III, apoM, apoA-I, and apoA-IV. Notably, we also identified seven isoforms of apoL-I and two isoforms of prenylcysteine lyase as new VLDL-associated proteins. Furthermore, we were able to identify PTM of apoE, which was found to be differently O-glycosylated at Thr212 residue, and PTM of apoL-I which we described, for the first time, to be phosphorylated at Ser296. While the physiological relevance of our finding remains to be assessed, we believe that our results will be useful as reference for future studies of VLDL structure in specific physiopathological conditions.
脂蛋白的生化研究揭示了它们的组成，对理解其功能有很大帮助。然而，由于其结构的复杂性，就组成成分和翻译后修饰（PTM）而言，深入的结构分析可能仍会揭示脂质代谢生理和病理过程中的重要参与者。在本研究中，我们使用二维电泳-基质辅助激光解吸电离飞行时间/串联飞行时间（2-DE MALDI-TOF/TOF）蛋白质组学方法绘制了极低密度脂蛋白（VLDL）的蛋白质图谱。鉴定出了几种与VLDL相关的载脂蛋白，包括载脂蛋白E的五种异构体、载脂蛋白C-IV的三种异构体，以及载脂蛋白C-III、载脂蛋白M、载脂蛋白A-I和载脂蛋白A-IV各一种异构体。值得注意的是，我们还鉴定出了载脂蛋白L-I的七种异构体和异戊烯基半胱氨酸裂解酶的两种异构体作为新的与VLDL相关的蛋白质。此外，我们能够鉴定出载脂蛋白E的翻译后修饰，发现其在苏氨酸212残基处存在不同程度的O-糖基化，以及我们首次描述的载脂蛋白L-I在丝氨酸296处的磷酸化。虽然我们这一发现的生理相关性仍有待评估，但我们相信我们的结果将为未来在特定生理病理条件下研究VLDL结构提供有用的参考。
