Title : Glycosylation and sialylation of macrophage-derived human
apolipoprotein E analyzed by
SDS-PAGE and mass spectrometry: evidence for a novel
site of glycosylation on
Ser290
Abstract :
- Apolipoprotein E ( apoE ) is a 34-kDa glycoprotein secreted from various cells including hepatocytes and macrophages and plays an important role in remnant lipoprotein clearance, immune responses, Alzheimer disease, and atherosclerosis
- Cellular apoE and plasma apoE exist as multiple glycosylated and sialylated glycoforms with plasma apoE being less glycosylated/sialylated than cell-derived apoE
- Some of the glycan structures on plasma apoE are characterized; however, the more complicated structures on plasma and cellular/secreted apoE remain unidentified
- We investigated glycosylation and sialylation of cellular and secreted apoE from primary human macrophages by one- and two-dimensional gel electrophoresis and mass spectrometry
- Our results identify eight different glycoforms with (HexNAc)(2)-Hex(2)-(NeuAc)(2) being the most complex glycan detected on Thr(194) in both cellular and secreted apoE
- Four additional glycans were identified on apoE ( 283-299 ), and using beta-elimination/alkylation by methylamine in vitro, we identified Ser(290) as a novel site of glycan attachment
- Comparison of plasma and cellular/secreted apoE from the same donor confirmed that cell-derived apoE is more extensively sialylated than plasma apoE
- Given the importance of the C terminus of apoE in regulating apoE solubility, stability, and lipid binding, these results may have important implications for our understanding of apoE biochemistry
Output (sent_index, trigger,
protein,
sugar,
site):
- 0. E, , apolipoprotein E, sialylation, -
- 0. Glycosylation, , apolipoprotein E, -, -
- 0. glycosylation, , -, -, site
- 0. sialylation, , apolipoprotein E, -, -
- 1. glycoprotein, , Apolipoprotein E, -, -
- 1. glycoprotein, , glycoprotein, -, -
- 2. glycosylated, , -, multiple glycosylated and sialylated glycoforms, -
- 2. glycosylated/sialylated, , apoE, -, -
- 2. sialylated, , -, multiple glycosylated and sialylated glycoforms, -
- 3. structures, , apoE, structures, -
- 4. apoE, , apoE, sialylation, -
- 4. glycosylation, , apoE, -, -
- 4. sialylation, , apoE, -, -
- 5. detected, , -, the most complex glycan, Thr(194)
- 7. sialylated, , apoE, -, -
Output(Part-Of) (sent_index,
protein,
site):
- 5. apoE, Thr(194)
- 8. apoE, terminus
*Output_Site_Fusion* (sent_index,
protein,
sugar,
site):
- 5. apoE, the most complex glycan, Thr(194)