Abstract
The protein bullous pemphigoid antigen‐2 (BPAG2/BP180/collagen type XVII) plays a key role in attachment of basal keratinocytes to epidermal basement membrane. The binding of BP180 with either integrin α6, integrin β4, or bullous pemphigoid antigen‐1 (BPAG1/BP230) is critical for this attachment in skin. The protein 14‐3‐3 σ, also known as stratifin and a marker for epithelial cells, is a member of a highly conserved small acidic 14‐3‐3 protein family naturally found in all eukaryotic cells. Here, we have used a 14‐3‐3σ GST pull‐down screening assay and showed that sigma (σ) isoform of the 14‐3‐3 protein family interacts with the cytoplasmic N‐terminal domain of BP180. Analysis of a series of truncated or deleted 14‐3‐3σ revealed that only intact 14‐3‐3σ molecule, but not any of its fragments can interact with BP180. This finding suggests that conformation and possible dimerization of 14‐3‐3 σ is essential for this interaction. Further, a BP180 co‐immunoprecipitation (IP) and its reverse IP assays were conducted and the results confirmed that 14‐3‐3 σ interacts with cytoplasmic domain, but not ecto‐domain of the BP180. In conclusion, the finding of this study provides evidence that 14‐3‐3σ isoform interacts with BP180 which is a major component of hemidesmosome involved in the attachment of epidermis to the basement membrane in skin. However, the significance of this interaction in hemidesmosome formation and/or attachment needs to be explored. J. Cell. Physiol. 212:675–681, 2007. © 2007 Wiley‐Liss, Inc.