IMMUNOSTAINING OF A HETERODIMERIC DERMATAN SULFATE PROTEOGLYCAN IS CORRELATED WITH SMOOTH MUSCLES AND SOME BASEMENT-MEMBRANES

A heterodimeric 760-kDa dermatan sulphate proteoglycan tentatively nam ed PG-760 was characterized as a product of keratinocytes, endothelial cells, and fibroblasts. The two core proteins of 460 kDa and 300 kDa are linked by disulphide bridges, and both carry one or only very few dermatan sulphate chains. Different antisera against PG-760 were used in the present study to investigate the distribution in selected murin e tissues by light and electron microscopy. PG-760 immunostaining was observed in cornea (epithelium including basement membrane, stroma, an d Descemet's membrane), skin, mucosa of the small intestine, Engelbret h-Holm-Swarm (EHS)-tumour (matrix and cells), and the smooth muscle la yers of uterus, small intestine, and blood vessels. No staining was ob served in capillaries, striated muscles, and liver parenchyma includin g the central vein. The expression of PG-760 in EHS-tumour was also de monstrated after extraction with 4 M guanidine and partial purificatio n by diethylaminoethyl (DEAE)-chromatography. We conclude that this no vel proteoglycan exhibits a unique tissue distribution being a constit uent of some but not all basement membranes, of some other extracellul ar matrices, and additionally, of all investigated smooth muscle layer s.