Synthesis
In brief, LPL is secreted from parenchymal cells as a glycosylated homodimer, after which it is translocated through the extracellular matrix and across endothelial cells to the capillary lumen. After translation, the newly synthesized protein is glycosylated in the endoplasmic reticulum. The glycosylation sites of LPL are Asn-43, Asn-257, and Asn-359. Glucosidases then remove terminal glucose residues; it is believed that this glucose trimming is responsible for the conformational change needed for LPL to form homodimers and become catalytically active. In the Golgi apparatus, the oligosaccharides are further altered to result in either two complex chains, or two complex and one high-mannose chain. In the final protein, carbohydrates account for about 12% of the molecular mass (55-58 kDa).
Homodimerization is required before LPL can be secreted from cells. After secretion, however, the mechanism by which LPL travels across endothelial cells is still unknown.
Read more about this topic: Lipoprotein Lipase
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