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J Verlinden

Publications and source records attributed to J Verlinden.

8 recordsLinked to original sources
PubMed1983

Identification of cell surface dipeptidylpeptidase IV in human fibroblasts.

An antigen with dipeptidylpeptidase IV activity was identified at the surface of normal human fibroblasts. Hydrophobic interaction electrophoresis in phenyl-Sepharose revealed that the enzyme contained a hydrophobic domain, while lactoperoxidase-catalysed iodination with 125I of living cells indicated that the protein was located at the cell surface. Crossed immunoelectrophoresis with specific antibodies of acid-extracted or papain-treated cells showed a shift of the dipeptidylpeptidase IV peak to a faster mobility. The molecular properties of the fibroblast enzyme were clearly different from those described for dipeptidylpeptidase IV from other tissues and species. Fibroblast dipeptidylpeptidase IV contained two different disulphide-linked subunits, of apparent Mr values 125000 and 135000 (denatured and reduced). In gel filtration, an Mr of about 400000 was observed for the unreduced molecule. The enzymic properties of fibroblast dipeptidylpeptidase IV were very similar to those of the well-characterized pig kidney enzyme. Activity towards glycyl-L-prolyl-beta-naphthylamide was inhibited 50% by 0.023 mM-di-isopropylphosphorofluoridate. L-Alanyl-L-alanyl-beta-naphthylamide was hydrolysed ten times more slowly than glycyl-L-prolyl-beta-naphthylamide.

Cell Membrane↗
PubMed1981

Immunochemical characterization of a 150 000 dalton human fibroblast surface glycoprotein.

The characterization of a human fibroblast surface glycoprotein, visualized by crossed immunoelectrophoresis using rabbit antibodies against whole fibroblasts, is described. The antigen is synthesized by fibroblasts in culture and was localized both intracellularly and at the cell surface. It was highly antigenic and was detected only in human cells of mesenchymal origin. The glycoprotein occurred in two different forms with alpha 2 and beta electrophoretic mobility. The slow migrating amphiphilic beta form was localized at the cell surface and showed a single protein band with an apparent molecular weight of 150 000 in SDS-polyacrylamide gel electrophoresis. By external papain treatment of intact viable cells, a water-soluble molecule was released with a reduced molecular weight (140 000) and an increased electrophoretic mobility as compared to the native membrane component. This hydrophilic form was also present intracellularly in fibroblasts not treated with exogeneous proteases. The observation that the detergent-solubilized beta form was irreversibly converted to a more anodic form by incubation of whole cell extract at acidic pH, suggested that the intracellular protein represented a lysosomal degradation product of native internalized fibroblast surface glycoprotein.

Antigens, Surface↗
PubMed1981

Localization of a highly antigenic human fibroblast surface glycoprotein (FSG) on fibroblasts and on epithelia involved in secretion or resorption.

The cellular distribution of a highly antigenic fibroblast glycoprotein, identified previously as aminopeptidase M, was studied in vitro by immunofluorescence and immuno-electron microscopy. The antigen was found to be localized at the surface of live and fixed fibroblasts in suspension and in cell layer; clustering or patching on live cells could be observed. Immunofluorescence after permeabilization of the cells with acetone showed distribution of the antigen in cytoplasmic granules. The tissue distribution of this antigen was examined by immunofluorescence on frozen sections of various human organs. In addition to fibroblasts, renal tubules, liver, pancreas and gut were found to react selectively with the antibody preparation. Moreover, a specific localization of the reaction product was observed. In the kidney the epithelium and brush border of the proximal convoluted tubules were stained. In the liver, the bile canaliculi reacted; in the pancreas the acinar cells and in the gut the brush border of the mucosal cells of the villi and crypts were stained. The same cells did not stain with an antiserum prepared in a similar fashion against another fibroblast component, or with preimmune IgG. In most sections of the selectively stained tissues, a predominant localization at the apical pole of the cells was observed. The localization of the antigen in different tissues corresponds with the distribution of aminopeptidase M, thereby confirming its identity and the antigenic cross-reaction between the fibroblast and tissue enzyme.

Aminopeptidases↗