CDNA CLONING AND EXPRESSION OF A NOVEL HUMAN DESMOCOLLIN

We have cloned a human cDNA encoding for a novel transmembrane protein from a bladder carcinoma cell line (HT-1376) cDNA library. Sequence a nalysis of this clone revealed an open reading frame of 2,691 bases en coding a protein of 896 amino acids. Sequence comparison showed that t his clone has significant homology to desmocollins, intercellular adhe sion molecules belonging to the cadherin superfamily. This protein con sists of a signal peptide of 30 amino acids, a precursor segment of 10 5 amino acids, and a mature protein of 761 amino acids. We expressed t his cDNA clone in COS1 cells and found that the predicted cell adhesio n molecule remained in the membrane fraction. Antibodies recognizing t he predicted mature adhesion molecule of the protein stained antigens along the cell boundaries of both HT-1376 cells and normal human kerat inocytes resembling the pattern of desmosome localization. These findi ngs suggest that our clone might be a new member of the desmocollin fa mily, and we have tentatively called this clone human desmocollin type 4.