A 155-KDA UNDERCOAT-CONSTITUTIVE PROTEIN OF CELL-TO-CELL ADHERENS JUNCTIONS

A fraction enriched in cell-to-cell adherens and tight junctions,vas i solated from the chick liver, and the undercoat-constitutive proteins were extracted from this isolated junctional fraction, Monoclonal anti bodies (mAbs),were then obtained by injecting this extract into rats, and five antigens were identified to be concentrated in the isolated j unctional fraction. We have characterized one mAb (E14 mAb) and its an tigen (E14). By immunoblotting of the isolated junctional fraction the E14 mAb reacted strongly with a single band of similar to 155 kDa, an d E14 was highly concentrated in the isolated junctional fraction. Imm unofluorescence microscopy revealed that the E14 mAb exclusively stain ed the junctional complex region of the liver, renal epithelial cells, and the cell-cell border of endothelial cells in various tissues. The intercalated disc of the heart was also significantly stained. Howeve r, the E14 signal was hardly detected from intestinal epithelial cells . By immunoelectron microscopy using renal epithelial cells, E14 was m ainly detected in the fibrous structures associated with the cell-to-c ell adherens junction. We conclude that E14 is a novel undercoat-const itutive protein found in certain types of cell-to-cell adherens juncti ons.