The lipoma preferred partner LPP interacts with α-actinin

Abstract

The lipoma preferred partner LPP is a member of the zyxin family of proteins. In this paper, we demonstrate that the structural similarities observed between zyxin and LPP also extend to their interaction capabilities. Similar to zyxin, LPP was found to bind to α-actinin in vitro. This interaction was confirmed in yeast and mammalian cells. Studies utilizing the three-hybrid system further indicated that zyxin and LPP compete for the same binding site in α-actinin. This site was mapped to the central rod of α-actinin, which contains spectrin-like repeats 2 and 3. In the case of LPP, a conserved motif present at the N-terminus was shown to be responsible for the interaction. Constructs lacking this motif did not bind to α-actinin in the yeast two-hybrid system and were not able to recruit α-actinin to an ectopic site in mammalian cells. Quantitative data obtained with the two-hybrid and the three-hybrid system suggest that LPP has a lower affinity for α-actinin than zyxin. It is likely that this difference leads to slightly different roles played by LPP and zyxin during the assembly and disassembly of focal adhesions.