Keratin cross-linking and epidermal transglutaminase. A review with observations on the histochemical and immunochemical localization of the enzyme.
Enzymes known as transglutaminases mediate cross-linking of polypeptide chains by epsilon-(gamma-glutamyl) lysine bonds. Such bonds stabilize structural proteins of many tissues; transglutaminases specific for these tissues have been identified. A calcium- and sulfhydryl-dependent transglutaminase with a molecular weight of 55,000 has been purified from bovine snout epidermis and used to elicit a specific antiserum to the enzyme. Sites of epidermal transglutaminase activity have been localized in the cytoplasm of upper malpighian and granular cells by two complementary methods. When thin-tissue sections were incubated with a fluorescent lysine analog(dansyl cadaverine) and calcium, tissue acceptor sites became fluorescent. Localization was confirmed by fluorescein-conjugated antibody labeling of the enzyme in situ. These observations indicate that epidermal transglutaminase cross-links epidermal proteins during the final stages of keratinization.
D000818:Animals; D000906:Antibodies / Q000032:analysis; D002417:Cattle; D003429:Cross Reactions; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D006801:Humans; D007106:Immune Sera / Q000032:analysis; D007633:Keratins / Q000032:analysis / Q000096:biosynthesis*; D008239:Lysine / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D012867:Skin / Q000201:enzymology* / Q000276:immunology / Q000378:metabolism; D005723:gamma-Glutamyltransferase / Q000032:analysis / Q000378:metabolism*
D000906:Antibodies; D007106:Immune Sera; D010455:Peptides; D007633:Keratins; D005723:gamma-Glutamyltransferase; D008239:Lysine