chylomicron => TG-depleted chylomicron + 50 long-chain fatty acids + 50 diacylglycerols

Stable Identifier
R-HSA-174757
Type
Reaction [transition]
Species
Homo sapiens
Compartment
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Lipoprotein lipase dimers (LPL:LPL) are tethered to heparan sulfate proteoglycans (HSPG) at endothelial cell surfaces (Fernandez-Borja et al. 1996; Peterson et al. 1992). Both syndecan 1 (Rosenberg et al. 1997) and perlecan (Goldberg 1996) HSPG molecules are capable of tethering LPL. The LPL enzyme catalyzes the hydrolysis and release of triacylglycerols (TG) associated with circulating chylomicrons to leave a CM remnant (CR). This reaction is annotated here as causing the hydrolysis and release of 50 molecules of TG. In vivo, the number is much larger, and TG depletion probably occurs in the course of multiple encounters between a chylomicron and endothelial LPL. This reaction is strongly activated by chylomicron-associated apo C-II protein both in vivo and in vitro (Jackson et al. 1986). Chylomicron-associated apoC-II protein inhibits LPL activity in vitro (Brown and Baginsky 1972), and recent studies have indicated a positive regulatory role for apoA-5 protein, though its molecular mechanism of action remains unclear (Marcais et al. 2005; Merkel and Heeren 2005). CRs can then be taken up by liver parenchymal cells in two ways; 1) directly by the LDL receptor or 2) apoE/HSPG-directed uptake by LDL receptor-related proteins.

Literature References
PubMed ID Title Journal Year
3942763 Comparison of apolipoprotein C-II-deficient triacylglycerol-rich lipoproteins and trioleoylglycerol/phosphatidylcholine-stabilized particles as substrates for lipoprotein lipase

Jackson, RL, Tajima, S, Yamamura, T, Yokoyama, S, Yamamoto, A

Biochim Biophys Acta 1986
5057882 Inhibition of lipoprotein lipase by an apoprotein of human very low density lipoprotein

Brown, WV, Baginsky, ML

Biochem Biophys Res Commun 1972
16200213 Apoa5 Q139X truncation predisposes to late-onset hyperchylomicronemia due to lipoprotein lipase impairment

Marcais, C, Verges, B, Charriere, S, Pruneta, V, Merlin, M, Billon, S, Perrot, L, Drai, J, Sassolas, A, Pennacchio, LA, Fruchart-Najib, J, Fruchart, JC, Durlach, V, Moulin, P

J Clin Invest 2005
1279089 Human lipoprotein lipase: relationship of activity, heparin affinity, and conformation as studied with monoclonal antibodies

Peterson, J, Fujimoto, WY, Brunzell, JD

J Lipid Res 1992
8728311 Lipoprotein lipase-mediated uptake of lipoprotein in human fibroblasts: evidence for an LDL receptor-independent internalization pathway

Fernandez-Borja, M, Bellido, D, Vilella, E, Olivecrona, G, Vilaro, S

J Lipid Res 1996
Participants
Participant Of
Catalyst Activity
Catalyst Activity
Title
lipoprotein lipase activity of GPIHBP1:HSPG:LPL dimer [plasma membrane]
Physical Entity
Activity
This event is regulated
Orthologous Events
Authored
Created