Chymotryptic cleavage of lipoprotein lipase

Lóokene, Aivar; Bengtsson‐Olivecrona, Gunilla

doi:10.1111/j.1432-1033.1993.tb17747.x

Cited by 53 publications

(46 citation statements)

References 43 publications

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“…3C). This finding is consistent with previous studies (39,40,43) that suggest that the COOHterminal domain of LPL may play a role in mediating the initial interaction of the lipase with lipoproteins and perhaps modulate the major type of particle with which either lipase will interact (42). Davis et al (41) conclude from their analysis of similar chimeric enzymes in which the COOH-terminal domains of LPL and HL are exchanged that the COOH-terminal domain of HL augments phospholipase function.…”

Section: Discussionsupporting

confidence: 82%

“…1) may play a role in determining the preferred substrate of the respective lipase (42). In addition, removal of the COOH-terminal 58 amino acids of LPL by chymotryptic cleavage resulted in the inability of LPL to bind to chylomicrons (43), suggesting that this region of the enzyme may mediate binding to lipoproteins. However, to date, the structural basis for the differences in substrate specificity between the two lipases remains poorly defined.…”

mentioning

confidence: 99%

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Human Hepatic and Lipoprotein Lipase: The Loop Covering the Catalytic Site Mediates Lipase Substrate Specificity

Dugi

Dichek

Santamarina-Fojo

1995

Journal of Biological Chemistry

124

104

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Section: Discussionsupporting

confidence: 82%

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confidence: 99%

Human Hepatic and Lipoprotein Lipase: The Loop Covering the Catalytic Site Mediates Lipase Substrate Specificity

Dugi

Dichek

Santamarina-Fojo

1995

Journal of Biological Chemistry

124

104

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“…The PL cofactor, procolipase, binds to the C-terminal domain of PL and interacts with the surface loop, presumably stabilizing the open form [18,19]. LPL requires the cofactor apoC-II for triolein hydrolysis, but not for tributyrin [31]. Despite the fact that the level of sequence conservation between apoC-II and procolipase is low, it is possible that a similar mechanism leading to a conformational change also produces the LPL open form.…”

Section: Discussionmentioning

confidence: 97%

Molecular modeling of the dimeric structure of human lipoprotein lipase and functional studies of the carboxyl‐terminal domain

Kobayashi

Nakajima

Inoue

2002

European Journal of Biochemistry

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Lipoprotein lipase (LPL) plays a key role in lipid metabolism. Molecular modeling of dimeric LPL was carried out using INSIGHT II based upon the crystal structures of human, porcine, and horse pancreatic lipase. The dimeric model reveals a saddle-shaped structure and the key heparinbinding residues in the amino-terminal domain located on the top of this saddle. The models of two dimeric conformations -a closed, inactive form and an open, active form -differ with respect to how surface-loop positions affect substrate access to the catalytic site. In the closed form, the surface loop covers the catalytic site, which becomes inaccessible to solvent. Large conformational changes in the open form, especially in the loop and carboxyl-terminal domain, allow substrate access to the active site. To dissect the structure-function relationships of the LPL carboxylterminal domain, several residues predicted by the model structure to be essential for the functions of heparin binding and substrate recognition were mutagenized. Arg405 plays an important role in heparin binding in the active dimer. Lys413/Lys414 or Lys414 regulates heparin affinity in both monomeric and dimeric forms. To evaluate the prediction that LPL forms a homodimer in a Ôhead-to-tailÕ orientation, two inactive LPL mutants -a catalytic site mutant (S132T) and a substrate-recognition mutant (W390A/W393A/ W394A) -were cotransfected into COS7 cells. Lipase activity could be recovered only when heterodimerization occurred in a head-to-tail orientation. After cotransfection, 50% of the wild-type lipase activity was recovered, indicating that lipase activity is determined by the interaction between the catalytic site on one subunit and the substraterecognition site on the other.Keywords: lipoprotein lipase; dimeric model structure; heparin binding; substrate recognition; catalytic activity.Lipoprotein lipase (LPL) belongs to a mammalian lipase family that includes pancreatic lipase (PL), hepatic lipase (HL), gastric lipase, and endothelial lipase [1,2]. The primary function of LPL is triglyceride hydrolysis in triglyceride-rich lipoproteins, such as chylomicron and very low density lipoprotein (VLDL) particles, which are converted to remnants. LPL is secreted from a variety of tissues, such as adipocyte, macrophage, and muscle cells, and is bound to the capillary bed of endothelium via cellular surface heparan sulfate proteoglycans (HSPG), a function reflected in LPL's strong affinity for heparin. LPL deficiencies in humans are manifested as severe hypertriglyceridemia [3-5] and arteriosclerosis [6]. Genetically engineered mice lacking LPL also exhibit hypertriglyceridemia. In addition to lipolytic activity, LPL functions as a ligand for lipoprotein receptors, such as low density lipoprotein (LDL) receptor, LDL receptor related protein (LRP), GP330/ LRP-2, and VLDL receptor [7][8][9][10][11].A model structure of LPL had previously been constructed, based on the crystal structure of human PL as a template [12]. The model structure exhibited two domainsa large N-t...

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“…In fact, Nikjaer et al 10 and Williams et al 11 demonstrated that a carboxylterminal domain of LPL binds to LDL receptorrelated peptides. On the other hand, there are some reports 16,17 suggesting that the carboxylterminal domain of LPL is important for lipid binding, although this particular region (396± 405) has not been speci®cally identi®ed. According to our present data, we suggest that this region of LPL contributes to either binding to cell surface heparan sulphate or binding to the chylomicrons.…”

Section: Discussionmentioning

confidence: 99%

Effect of lipoprotein lipase on binding of chylomicrons to LDL receptor-deficient Chinese hamster ovary cells

Kobayashi

Tashiro²,

Bujo³

et al. 2001

Ann Clin Biochem

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SUMMARY. The authors investigated the binding of human plasma125 I-labelled chylomicrons to Chinese hamster ovary (CHO) cells, i.e. native CHO cells are mutant ldl-A7 cells lacking the low-density lipoproteins receptor, in the absence and presence of exogenous bovine milk lipoprotein lipase (LPL) in the culture medium. Only a small amount of binding to either cell was observed in the absence of added LPL. Exogenously added LPL increased the speci®c binding of chylomicrons to ldl-A7 cells, as well as to native CHO cells. The enhanced binding of chylomicrons to ldl-A7 cells or native CHO cells by LPL was inhibited by heparinase and a monoclonal antibody against LPL (5D2) which recognizes the carboxyl terminal of LPL. However, the enhanced binding was not inhibited by 1 M NaCl, which abolishes the enzymatic activity of LPL in either ldl-A7 cell or native CHO cells. These results suggest that LPL enhances the binding of chylomicrons to heparan sulphate proteoglycans of CHO cells, and that it is the carboxyl terminal of LPL but not the enzymatic activity of LPL that is essential for LPL to mediate the binding of chylomicrons to CHO cells.Lipoprotein lipase (LPL) is a lipolytic enzyme which catalyses the hydrolysis of triglycerides in triglyceride-rich lipoproteins (TRLP), such as very low-density lipoprotein (VLDL) and chylomicrons. This hydrolysis requires TRLP binding to LPL, which is anchored to the endothelial cell by heparan sulphate proteoglycans (HSPG).LPL is known to mediate the binding of all classes of lipoproteins, such as chylomicrons, VLDL, low-density lipoproteins (LDL) and high-density lipoproteins (HDL), to a variety of cells, such as Hep G2 cells, ®broblasts and macrophages, 1±7 and it is speculated that this process does not depend on the hydrolytic function of the enzyme. LPL has high binding af®nity for HSPG, and several studies 3±5,8,9 suggest that these cell-surface molecules may be involved in the LPL-mediated enhanced binding of lipoproteins to cultured cells. It was reported that the binding of apolipoprotein E liposomes to the a 2 -macroglobulin/LDL receptor-related protein (LRP) is increased in the presence of LPL.3 Moreover, several studies 10,11 have demonstrated that the carboxyl terminal domain of LPL binds to the LDL receptor. However, the molecular mechanisms of LPLmediated lipoproteins binding to cells are still controversial. The availability of the ldl-A7 cells or the LDL receptor-de®cient Chinese hamster ovary (CHO) cells gave us a unique opportunity to investigate the effect of LPL on the binding of lipoproteins to cells. In this study we investigated the effects of LPL on the binding of chylomicrons to the cell surface and its possible mechanisms, using a series of CHO cells, namely, native CHO cells and ldl-A7 cells. MATERIALS AND METHODSMutant CHO cells lacking the LDL receptor (ldl-A7) 12 were kindly provided by Dr Monty Krieger (Massachusetts Institute of Technology).CHO cells were grown in HAM-F12 medium with 10% foetal calf serum, and the medium was changed to HAM-F12 ...

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Chymotryptic cleavage of lipoprotein lipase

Cited by 53 publications

References 43 publications

Human Hepatic and Lipoprotein Lipase: The Loop Covering the Catalytic Site Mediates Lipase Substrate Specificity

Human Hepatic and Lipoprotein Lipase: The Loop Covering the Catalytic Site Mediates Lipase Substrate Specificity

Molecular modeling of the dimeric structure of human lipoprotein lipase and functional studies of the carboxyl‐terminal domain

Effect of lipoprotein lipase on binding of chylomicrons to LDL receptor-deficient Chinese hamster ovary cells

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