Liver Plasma Membrane: the Source of High Molecular Weight Alkaline Phosphatase in Human Serum

Broe, Marc E. De; Roels, Frank; Nouwen, Etienne J.; Claeys, L; Wieme, R.J.

doi:10.1002/hep.1840050124

Cited by 80 publications

(37 citation statements)

References 72 publications

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“…This aggregated form of AP is low in the serum of healthy individuals but is increased in hepatobiliary diseases, especially choleostasis. It presumably includes both enzyme-lipid complexes and membrane fragments to which AP is still attached [570,571]. The physiological role of serum AP remains an open question.…”

Section: Glycosylationmentioning

confidence: 99%

Cellular function and molecular structure of ecto-nucleotidases

Zimmermann

Zebisch

Sträter

2012

Purinergic Signalling

891

922

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Ecto-nucleotidases play a pivotal role in purinergic signal transmission. They hydrolyze extracellular nucleotides and thus can control their availability at purinergic P2 receptors. They generate extracellular nucleosides for cellular reuptake and salvage via nucleoside transporters of the plasma membrane. The extracellular adenosine formed acts as an agonist of purinergic P1 receptors. They also can produce and hydrolyze extracellular inorganic pyrophosphate that is of major relevance in the control of bone mineralization. This review discusses and compares four major groups of ectonucleotidases: the ecto-nucleoside triphosphate diphosphohydrolases, ecto-5′-nucleotidase, ecto-nucleotide pyrophosphatase/phosphodiesterases, and alkaline phosphatases. Only recently and based on crystal structures, detailed information regarding the spatial structures and catalytic mechanisms has become available for members of these four ecto-nucleotidase families. This permits detailed predictions of their catalytic mechanisms and a comparison between the individual enzyme groups. The review focuses on the principal biochemical, cell biological, catalytic, and structural properties of the enzymes and provides brief reference to tissue distribution, and physiological and pathophysiological functions.

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Section: Glycosylationmentioning

confidence: 99%

Cellular function and molecular structure of ecto-nucleotidases

Zimmermann

Zebisch

Sträter

2012

Purinergic Signalling

891

922

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“…In cholestatic mainly localized at the canalicular membrane, which liver disease, they often circulate as high-molecularis in agreement with previous results. 2 In the human mass forms, generated by shedding of LiPMF, which kidney, LAP activity was distributed throughout the results in vesicular structures expressing the different entire proximal tubules, as described by Guder and membrane-bound enzymes at their surface, such as Ross. 25 Detailed morphological analysis of the isolated ALP, g-GT, LAP, and 5-Nu.…”

Section: Electron Microscopical Study Of Immunoprecipitatedmentioning

confidence: 97%

“…17 Precipitates were processed for electron treatment with AD-1, the Mem-LiALP band was remicroscopy as was described for tissue specimen. 2 They were tarded ( Fig. 1).…”

Section: Isolation Of Mem-lialp Bearing Vesicles (Lipmf) Frommentioning

confidence: 99%

“…25 Detailed morphological analysis of the isolated ALP, g-GT, LAP, and 5-Nu. 2 Shedding of plasma memLiPMF by electron microscopy was indicative of their brane fragments is a well-described phenomenon in high purity and their membrane nature. Furthermore, many cells, especially in malignant cells and in hepatoantibody binding during their isolation, did not perturb cytes under pathological conditions.…”

Section: Electron Microscopical Study Of Immunoprecipitatedmentioning

confidence: 99%

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Purification of circulating liver plasma membrane fragments using a monoclonal antileucine aminopeptidase antibody

Deng

1996

Hepatology

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presently show that AD-1, a specific monoclonal antibody originally produced against MemliALP, reacts with physical, morphological, histochemical, and immuno-LAP, a constituent of the human liver plasma mem-logical evidence. Shedding of hepatocyte plasma membrane. Using AD-1 as an immunosorbant, we isolated cir-branes is thought to be involved in the release of memculating LiPMF from cholestatic sera to a high level of brane-bound liver alkaline phosphate (Mem-LiALP) purity and separated it from other high-molecular-mass into the circulation. 3 Because of its structural characmaterial, such as liver ALP Ç lipoprotein-X complexes. teristics, high molecular mass liver ALP was recently These purified membrane fragments retained their bio-renamed Mem-LiALP. 4 Several studies using different chemical characteristics. Glycosyl-phosphatidylinositol supporting media during electrophoresis, such as agar, anchor bearing liver ALP (Anch-LiALP) could be reagarose, starch, polyacrylamide gel, and cellulose ace- 5,6 Beglycosyl-phosphatidylinositol anchor following deter-cause of its sensitivity and specificity, Mem-LiALP has gent solubilization of the enzyme. Serum LiPMF from been advanced as a serum marker of hepatic metastapatients with different kinds of cholestatic liver disease sis. 4,7,8 were bound onto AD-1 coated nitrocellulose disks and Several other membrane-bound enzymes, such as gthe activity of four membrane-bound enzymes (LAP, glutamyltransferase (g-GT), leucine aminopeptidase ALP, 5Nu, g-GT) was analyzed. A considerable interindi-(LAP), and 5-nucleotidase (5-Nu) are present in the vidual variation of enzyme activities was observed, sug-membrane of the shedded vesicles. Both ALP and 5-Nu are attached to the plasma membrane by means of a glycosyl-phosphatidylinositol anchor (GPI-anchor), Abbreviations: ALP, alkaline phosphatase; LiPMF, liver plasma membrane and can be released in vitro by the action of GPI-specific fragments; MemLiALP, membrane-bound liver alkaline phosphate; g-GT, gglutamyltransferase; LAP, leucine aminopeptidase; 5-Nu, 5-nucleotidase; phospholipase-C (GPI-PLC).9,10 The precise mechanism GPI, glycosyl-phosphatidylinositol; GPI-PLC, GPI-specific phospholipase-C;of the in vivo release of these enzymes and the role of (GPI-PLD), abundantly present in serum, might be re- Received December 30, 1994; accepted October 3, 1995. sponsible for the in vivo release of GPI-anchored proSupported by grants from the Sportvereniging tegen Kanker and the Vereteins.11 Shedded plasma membrane vesicles are easily niging voor Kankerbestrijding, Brussels, Belgium.

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“…A report of an elaborate study by De Broe et ai. 93 has been published recently which demonstrates that at least part of the high molecular weight alkaline phosphatase in human plasma is of sinusoidal origin.…”

Section: Historymentioning

confidence: 99%