Characterization of Apolipoprotein M Isoforms in Low-Density Lipoprotein

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• 作者：Helen Karlsson ; Helen Lindqvist ; Christer Tagesson ; Mats Lindahl
• 刊名：Journal of Proteome Research
• 出版年：2006
• 出版时间：October 2006
• 年：2006
• 卷：5
• 期：10
• 页码：2685 - 2690
• 全文大小：278K
• 年卷期：v.5,no.10(October 2006)
• ISSN：1535-3907

文摘

Apo M is a recently discovered human lipoprotein thought to be involved in the metabolism of lipidsand lipoprotein particles. Here, a proteomic approach was applied to examine the glycosylation patternof apo M in human LDL. We treated LDL proteins with N-glycosidase or neuraminidase, studied mobilityshifts of Apo M by two-dimensional gel electrophoresis, and different isoforms were then identifiedwith mass spectrometry. This way, we demonstrated the presence of five isoforms of apo M in LDL:three that are both N-glycosylated and sialylated, one that is N-glycosylated but not sialylated, andone that is neither N-glycosylated nor sialylated. As judged from the examination of LDL from 20 healthyhuman subjects, the three N-glycosylated and sialylated forms are most abundant (80-100% of thetotal apo M in LDL) whereas the unsialylated and unglycosylated variants constitute at most 20%.Comparative analysis showed that the same five isoforms of apo M are also present in HDL. Furtherstudies aiming at elucidating the role of apo M in health and disease will have to take this polymorphismof apo M proteins into account.