Identification and characterization of a soluble form of the plasma cell membrane glycoprotein PC‐1 (5′‐nucleotide phosphodiesterase)

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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“…Soluble forms have also been described for NPP1 [365,417], NPP3 [422], NPP6 [388], and NPP7 [423]. E-NPPs are found in human serum [152,424,425].…”

Section: Soluble Formsmentioning

confidence: 98%

“…Glycosylation N-glycosylation of E-NPPs accounts for up to 20 kDa of the molecular weights of NPP1-NPP3 [398,417,418]. N-glycosylation is not required for the apical targeting of NPP3 [419].…”

Section: General Molecular Propertiesmentioning

confidence: 99%

Cellular function and molecular structure of ecto-nucleotidases

Zimmermann

Zebisch

Sträter

2012

Purinergic Signalling

879

922

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“…Lane A contains the molecular mass markers (top to bottom) 116, 94 and 66 kDa. N-glycanase, the apparent molecular mass of soluble human PC-1 (see [19]) decreased from 120 kDa to 90 kDa (data not shown) .…”

Section: N-glycanase Sensitivity Of Pc-1mentioning

confidence: 99%

“…Beads were collected by brief centrifugation, washed three times in 50 mM TrisEICl, 0.6 M NaC1, 0.5% Triton X-100, pH 8.2, then resuspended in SDS-sample buffer [31]. Mouse PC-1 was immunoprecipitated from pLs.lcells as previously described [19]. Bound proteins were eluted by heating for 2 min at 100°C and analyzed by SDS/ PAGE.…”

Section: Immunoprecipitationmentioning

confidence: 99%

Biochemical Characterization of Human PC‐1, an Enzyme Possessing Alkaline Phosphodiesterase I and Nucleotide Pyrophosphatase Activities

Belli

Goding

1994

European Journal of Biochemistry

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) -EJB 94 0666/4 PC-1 is an ecto-enzyme possessing alkaline phosphodiesterase I and nucleotide pyrophosphatase activities. In this paper, we demonstrate the expression, biochemical characterization and biosynthesis of human PC-1. Previously, there has been uncertainty concerning which of two methionine residues is the initiator. It is now shown that expression of PC-1 is much greater if the first methionine residue is present, and that the sequence between the two methionine residues is translated in both human and mouse, in both transfected cells and cells naturally expressing PC-1. The first methionine residue is therefore the initiator. Human PC-1 is capable of autophosphorylation, and conditions are described in which PC-1 is the only labelled phosphoprotein on the plasma membranes of intact cells, allowing the demonstration that the mature membrane form of human PC-1 is approximately 10 kDa larger than that of the mouse form. Pulse-chase biosynthetic studies and treatment with two different endoglycosidases show that most of this difference is due to N-linked oligosaccharides. The polypeptide backbone of human PC-1 is 20 amino acids longer than that of the mouse PC-1, with most of the difference in polypeptide chain length being in the cytoplasmic domain. The revised cytoplasmic domain of human PC-1 has 76 amino acids, while the mouse cytoplasmic domain has 58 amino acids. Optimal alignment of mouse and human cytoplasmic domains reveals areas of sequence conservation in which the third bases vary. It is suggested that these regions of conservation may point to functionally important sequences in the cytoplasmic domain.PC-1 is a disulphide-bonded homodimeric type-I1 transmembrane glycoprotein which has recently been shown to be identical to both alkaline phosphodiesterase I and nucleotide pyrophosphatase [1, 21. It is expressed on plasma cells, the distal convoluted tubule of the kidney, epididymis, salivary gland ducts, capillary endothelium in the brain, and chondro-

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“…14 The protein was found also in a soluble form in the serum of normal mice and in the culture medium of mouse plasmocytomas. 15 Furthermore, during the last few years two other proteins with this activity were identified. One of these is autotaxin, a 125-kd soluble factor secreted by a human melanoma cell line.…”

mentioning

confidence: 99%

Identification of B10, an alkaline phosphodiesterase of the apical plasma membrane of hepatocytes and biliary cells, in rat serum: Increased levels following bile duct ligation and during the development of cholangiocarcinoma

et al. 1998

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Alkaline phosphodiesterase (APDE) is associated with the cellular plasma membrane of many organs. Several isoforms are also detected in normal human serum and their respective amounts vary in liver diseases but their significance is unknown. The aims of this study were: 1) to identify a serum form of B10, an APDE exclusively localized at the apical pole of the plasma membrane of rat hepatocytes and biliary cells; 2) to gain insight into its origin; and 3) to investigate its behavior, in two liver diseases in which an abnormal membrane expression of B10 has been reported, namely cholestasis and cholangiocarcinoma. A soluble form of B10 was immunoprecipitated from normal rat serum, which amounted to 13% of total serum APDE activity. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the size of the serum enzyme was 125 kd, which is slightly lower than that found in the plasma membrane (130 kd). In bile, a 120-kd and a 130-kd form was found. A sixfold and fivefold increase of B10 APDE activity was observed in the serum of bile duct-ligated rats and in the Long-Evans Cinnamon (LEC) rats which spontaneously develop cholangiocarcinoma. The molecular size of the form present in serum was unchanged. A threefold increase was also observed in LEC rats which had not yet developed a cholangiocarcinoma. In conclusion, we identified a soluble form of B10 in normal rat serum. The increase in serum B10 in the experimental and pathological conditions investigated does not seem to result from passage of the biliary form to the serum but seems to be caused by increased cleavage of the membrane form. Its rise early during the onset of cholangiocarcinoma suggests that B10 in the serum might be a marker of carcinogenesis and/or be involved in the development of cholangiocarcinoma.

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Identification and characterization of a soluble form of the plasma cell membrane glycoprotein PC‐1 (5′‐nucleotide phosphodiesterase)

Cited by 96 publications

References 32 publications

Cellular function and molecular structure of ecto-nucleotidases

Cellular function and molecular structure of ecto-nucleotidases

Biochemical Characterization of Human PC‐1, an Enzyme Possessing Alkaline Phosphodiesterase I and Nucleotide Pyrophosphatase Activities

Identification of B10, an alkaline phosphodiesterase of the apical plasma membrane of hepatocytes and biliary cells, in rat serum: Increased levels following bile duct ligation and during the development of cholangiocarcinoma

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