Description
Desmocollin-3 is a 100-110kD type I transmembrane glycoprotein that belongs to the cadherin family of calcium dependent adhesion molecules (1-3). The human Desmocollin-3 is synthesized with a 108 amino acid (aa) propeptide. The mature protein consists of a 555 aa extracellular domain (ECD) that contains five cadherin-like domains, a 21 aa transmembrane segment, and a 185 aa cytoplasmic domain (4, 5). Within the ECD, human Desmocollin-3 shares 78% aa sequence identity with mouse and rat Desmocollin-3. It shares 52% and 64% aa sequence identity with Desmocollin-1 and -2, respectively. A splice variant of human Desmocollin-3 has a truncated and substituted cytoplasmic domain (4, 6). Desmocollin-3 is one of the principal components of desmosomes which form adhesive contacts between epithelial cells (1, 2). It is expressed in the basal and suprabasal layers of stratified epithelia in many tissues (5, 7, 8). Desmocollin-1 and -2, by contrast, are preferentially localized in the more superficial layers (7). In mouse, Desmocollin-3 is expressed throughout embryogenesis and is required for non-desmosomal functions during early development (9, 10). During apoptosis, both isoforms of Desmocollin-3 are proteolytically cleaved by caspases and metalloproteases (11). Desmocollin-3 can be upregulated or downregulated in carcinoma (6, 12, 13).
A DNA sequence encoding the extracellular domain of human Desmocollin-3 (DSC-3; Arg 136-Lys 690; Accession # Q14574) was fused to a 6x histidine tag at the c-terminus. The protein was expressed in a mouse myeloma cell line, NSO