Endogenous lectin from terminally differentiated epidermal cells.
We isolated a concanavalin A (Con-A)-binding glycoprotein from human stratum corneum by nonionic detergent extraction, lectin affinity chromatography, and preparative gel electrophoresis. This glycoprotein migrates as a single band at 40 kilodaltons at sodium-dodecyl-sulfate gel electrophoresis with or without the presence of 2-mercaptoethanol. It was shown to have a heterogeneous distribution between pH 5.6 and 7.6 by isoelectric focusing. The glycoprotein is histidine rich (10.4%) but is distinct from other histidine-rich proteins (epidermal filaggrin and the histidine-rich glycoprotein from serum). It does not bind to lectins specific for L-fucose or alpha-D-galactose. We prepared a monospecific polyclonal antibody to the 40-kilodalton glycoprotein; at the ultrastructural level, it cytoimmunolocalizes exclusively to the membranes of the stratum corneum. A unique feature of the glycoprotein is that it is an endogenous lectin: it hemagglutinates trypsinized and gluteraldehyde-fixed rabbit erythrocytes. The inhibition of its hemagglutination was found to be greatest with amino sugars, down to a saccharide concentration of 10(-5) mM. Such a high affinity of binding at the cell surface suggests that this glycoprotein is a major carbohydrate-binding, cross-linking molecule that holds adjacent corneocytes together in the stratum corneum. We hypothesize that this lectin plays a role in the adhesion and desquamation of the stratum corneum.
D000596:Amino Acids / Q000032:analysis; D002454:Cell Differentiation; D002846:Chromatography, Affinity; D003208:Concanavalin A / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D000078404:Epidermal Cells; D004817:Epidermis / Q000032:analysis*; D000091344:Filaggrin Proteins; D005455:Fluorescent Antibody Technique; D006023:Glycoproteins / Q000032:analysis* / Q000302:isolation & purification; D006386:Hemagglutination Tests; D006801:Humans; D007525:Isoelectric Focusing; D037102:Lectins / Q000032:analysis* / Q000302:isolation & purification; D008854:Microscopy, Electron
D000596:Amino Acids; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D006023:Glycoproteins; D037102:Lectins; D003208:Concanavalin A