Glycoproteins and glycosaminoglycans of cultured normal human epidermal keratinocytes

[3H]glucosamine has been used to label metabolically keratinocyte cell-surface glycoconjugates. The major labelled bands identified on sodium dodecyl sulphate/polyacrylamide gels had apparent molecular weights of greater than 250 000, and 150 000-80 000. Most of these components were trypsin-sensitive, indicating that the label was protein-bound. Some of the labelled components were shown to be proteoglycans and the labelled glycosaminoglycans released from them by trypsin were identified as hyaluronic acid (54%), heparan sulphate (33%) and chondroitin sulphate (13%). Specific immunological methods (immunoperoxidase staining and immunoprecipitation) showed that keratinocytes produced fibronectin. Immunoperoxidase staining showed keratinocytes produce only small ‘stitches’ of fibronectin at cell edges; no large fibrils were seen nor any staining over or between cells.