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McComb, Robert B.; Bowers, George N.; Posen, Solomon

doi:10.1007/978-1-4613-2970-1_3

Cited by 9 publications

(8 citation statements)

References 731 publications

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“…AP-ase is a glycoprotein distributed in many organs of mammals [19]. Con A chromatography was used to iso late AP-ase from different organs [20], Koyoma et al [20] found that the elution profile of AP-ase from a Con A col umn was different in different organs.…”

Section: Discussionmentioning

confidence: 99%

Abnormal Glycosylation of Duodenal Membranous Alkaline Phosphatase Induced by Cysteamine in Rats

Japundzić

Kosaric²

1994

Digestion

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The membranous and soluble isoenzymes of alkaline phosphatase (AP-ase) were isolated from the duodenal mucosal cells in control and cysteamine-treated rats. Both the cytosolic and membranous isoenzymes of the AP-ase were drastically inhibited by a single subcutaneous injection of cysteamine-HCl, a potent duodenal ulcerogen. However, cysteamine did not change the isoenzyme distribution between the two compartments of the duodenal mucosal cells. Membranous isoenzyme of duodenal AP-ase in control rats was separated by concanavalin A (Con A) affinity chromatography into three fractions: unbound (65%), weakly bound (11 %) and strongly bound (24%). The strongly bound fraction disappeared completely from duodenal mucosal cells of cysteamine-treated rats before any visible signs of ulcer formation. Since the strongly bound fraction of AP-ase contains high mannose-type sugar chains, we concluded that the ulcerogen affected the initial mannosylation (or glypiation) of membranous AP-ase which took place in the rough endoplasmic reticulum of the mucosal cells. In control rats, the Con A fractions of the membranous AP-ase were separated by gel filtration as tetramers of M_r 420 and 340 kD and dimers of M_r 185-200 kD. In cysteamine-treated rats, neither the strongly bound tetramers of 340 kD nor dimers of 185 kD were found by gel filtration. However, cysteamine did not change the total tetramer:dimer ratio. Judging by the decrease of V_max values at the pH optimum, the different molecular forms of the AP-ase are selectively sensitive to cysteamine inhibition. The kinetic data show that the type of the tissue-specific inhibition by cysteamine is different for dimeric and tetrameric forms of the membranous AP-ase. It is of an ‘uncompetitive’ type for a tetrameric form and of a ‘non-competitive’ type for dimeric forms.

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Section: Discussionmentioning

confidence: 99%

Abnormal Glycosylation of Duodenal Membranous Alkaline Phosphatase Induced by Cysteamine in Rats

Japundzić

Kosaric²

1994

Digestion

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“…TN-AP expression in vascular endothelial and renal proximal tubular cells has been used as a cell-specific marker to distinguish them from other cells [9,23]. Our data suggest that high TN-AP expression is a cell functionrelated marker, and the function is cell spe cific.…”

Section: Discussionmentioning

confidence: 69%

“…TN-AP expression at very high levels is known for renal proximal tubular cells [8,9], However, the exact physiological function of TN-AP in the kidney is unknown. Because of the existence of at least two isoforms of AP in the kidney [19] and the functional similarity of these isoforms [20], human cases with sin gle TN-AP gene deficiency [11] or transgenic mice with TN-AP gene knocked out [12] may not help reveal TN-AP physiological function in kidney.…”

Section: Discussionmentioning

confidence: 99%

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Tissue Non-Specific Alkaline Phosphatase May Be a Function-Related Marker in Renal Proximal Tubular Epithelia and in Vascular Endothelia as It Is in Osteoblasts

Hui¹,

Cheng²

1996

Cell Physiol Biochem

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Tissue non-specific alkaline phosphatase (TN-AP) is a multifunctional phosphatase and has a variety of substrates in vitro. In adults, TN-AP is highly expressed in osteoblasts, renal proximal tubular epithelia and vascular endothelia. In osteoblasts, it is well known that TN-AP plays an important role in bone mineralization. Considering its many activities in vitro, we hypothesize that TN-AP also plays a role in regulating cellular activities in renal proximal tubular epithelia and vascular endothelia. By using a stable gene transfection technique, we transfected two cell lines with a rat TN-AP gene, one renal proximal tubule-like (LLC-PK1), another vascular endothelia-like (Py-4-1). The effect of TN-AP expression was cell specific. In Py-4-1 cells, the forced TN-AP expression stimulates cellular behaviours associated with terminal differentiation. This suggests that in vivo AP expression in certain vascular endothelia may mark a terminal-differentiated subpopulation with less angiogenic potential. While, in LLC-PK1 cells, the forced TN-AP expression inhibited cellular transport function as demonstrated by delayed dome formation. By inference, TN-AP expression in renal proximal tubule in vivo should have a regulatory role in cellular transport. Our data suggest that TN-APs have roles as function-related markers in renal proximal tubular epithelia and vascular endothelia.

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“…APases are glycoproteins distributed in many organs of mammals [6]. Koyama et al [7] found that the elution profile of APases from a Con A-Sepharose column (Con A) was different in different organs.…”

Section: Introductionmentioning

confidence: 99%

Microheterogeneity of Rat Serum Alkaline Phosphatase in Fasting State: Characterization of Two Duodenal Alkaline Phosphatase Glycoforms

1997

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Using concanavalin A-Sepharose affinity chromatography (Con A) we found that the serum of normal fasted adult rats contains two alkaline phosphatase (APase) glycoforms, one weakly bound (II) and the other strongly (III) bound to the column. Both serum APase glycoforms had an apparent molecular mass of 163 kD on Sepharose CL-6B and 118 kD on SDS-PAGE under nondenaturing conditions. We consider the molecular forms as dimeric, since monomers of 60.3 and 58.5 kD for the Con A weakly and strongly bound glycoform, respectively, were obtained. However, these two dimeric glycoforms were different in their pH optimum, affinity to p-nitrophenyl phosphate as substrate, the degree of L-phenylalanine inhibition and relative thermostability. Judging by the relative thermostability and by L-phenylalanine inhibition, it seems that both serum APase glycoforms in fasted rats are mainly of duodenal mucosal cell origin. The Con A weakly bound (II) glycoform could be derived from the cytosol, and the Con A strongly bound (III) one from both the cytosolic and membranous fractions of duodenal mucosal cells. However, in addition to the heat-stable component, the Con A strongly bound serum APase glycoform also contains a minor heat-labile and L-phenylalanine-resistant component which could be of nonspecific tissue origin since such a fraction was not discovered by us in rat duodenal mucosal cells.

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Distribution in Nature

Cited by 9 publications

References 731 publications

Abnormal Glycosylation of Duodenal Membranous Alkaline Phosphatase Induced by Cysteamine in Rats

Abnormal Glycosylation of Duodenal Membranous Alkaline Phosphatase Induced by Cysteamine in Rats

Tissue Non-Specific Alkaline Phosphatase May Be a Function-Related Marker in Renal Proximal Tubular Epithelia and in Vascular Endothelia as It Is in Osteoblasts

Microheterogeneity of Rat Serum Alkaline Phosphatase in Fasting State: Characterization of Two Duodenal Alkaline Phosphatase Glycoforms

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