Enzymatic cross-linking of involucrin and other proteins by keratinocyte particulates in vitro.
A transglutaminase-catalyzed cross-linking process characteristic of keratinocytes leads to the formation of the insoluble corneocyte envelope. The essentials of this process take place in vitro in a reconstituted system derived from subcellular fractions. A particulate fraction containing membrane-bound envelope precursor proteins and the enzyme transglutaminase is combined with cytosolic proteins; when the enzyme is activated by Ca++, cytosolic proteins are removed from solution and cross-linked to particulate proteins. This interaction is cell-type-specific, since particulates derived from fibroblasts and also containing transglutaminase activity cannot substitute for those of keratinocytes. Involucrin, a cytosolic protein known to be a precursor of the envelope, is more efficiently cross-linked than other cytosolic proteins. The cross-linking of proteins of the particulate fraction (membrane proteins) is promoted by the presence of involucrin.
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D000217:Acyltransferases / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D003600:Cytosol / Q000201:enzymology; D004817:Epidermis / Q000201:enzymology* / Q000648:ultrastructure; D006801:Humans; D007633:Keratins / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D008565:Membrane Proteins / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism*; D011700:Putrescine / Q000378:metabolism; D011503:Transglutaminases
D046911:Macromolecular Substances; D008565:Membrane Proteins; D011498:Protein Precursors; C032253:involucrin; D007633:Keratins; D000217:Acyltransferases; D011503:Transglutaminases; D011700:Putrescine