The role of the coiled-coil motif in interactions mediated by TPD52

TPD52 (D52)-like proteins are small coiled-coil motif-bearing proteins first identified through their expression in human breast carcinoma that mutually interact in hetero- and homomeric fashions. However, it has been unclear whether the coiled-coil motif is sufficient, or even necessary, for these interactions to occur. We have therefore examined the binding activities of a panel of C-terminally deleted D52 proteins in both the yeast two-hybrid system and pull-down assays. In the yeast two-hybrid system, interactions were only detected when regions C-terminal to the coiled-coil motif were also present. However, using pull-down assays, interactions were detected for all deletion mutants which included the coiled-coil motif. This suggests that the coiled-coil motif is indeed necessary for interactions mediated by D52 proteins, but that C-terminal protein regions facilitate and/or stabilize these interactions. (C) 2001 Academic Press.