Structure of the human desmoplakins. Implications for function in the desmosomal plaque.
The structure of the carboxy-terminal domain is dominated by six highly homologous repeats that also occur in lesser number in desmoplakin (3 repeats; Green et al., 1990), bullous pemphigoid antigen (BPAG) 1 (2 repeats; Sawamura et al., 1991), and the recently identified envoplakin (1 repeat; Ruhrberg et al., 1996).
Envoplakin, a novel precursor of the cornified envelope that has homology to desmoplakin. J.
The interaction between the C-terminus of desmoplakin - the major protein in the cytoplasmic portion of the desmosomes (DP.CT) - and various IF family members has been accessed by yeast two-hybrid analyses.
Two hybrid analysis reveals fundamental differences in direct interactions between desmoplakin and cell type specific intermediate filaments.
CHEN: In your two-hybrid system you only use the C-terminus of desmoplakin. Do you think your results would change if you put the C-terminus in the context of the whole molecule?
Since dimerization of desmoplakin is mediated by dimerization of its rod domain, we had hoped that expression of the entire rod domain plus the C-terminus would enhance the activity somewhat.
CHISHOLM: When you add the Type I and Type II keratin together with the desmoplakin tail, is the idea that you are actually forming a dimer between those two, and that somehow that dimer is now providing the DNA-binding domain together with the desmoplakin tail and the activating domain?