Selectivity in subunit composition of EnaNASP tetramers

Abstract

EnaNASP proteins have an established role in regulating actin dynamics in diverse cell types. The mammalian EnaNASP family members, Mena, VASP, and EVL have many overlapping activities. However, the three family members are not equivalent and each possess a number of features that are absent in the others. Unique modes of regulation and paralog-specific interacting partners point to potential differences in the activity and function of EnaNASP proteins. The function of this family of proteins relies on their ability to form tetramers via a highly conserved tetramerization domain located at the Cterminus of all EnaNASP proteins. The potential formation of mixed tetramers may combine the unique aspects of each paralog into one molecule. Here, I describe a series of immunoprecipitation experiments to evaluate hetero-oligomerization of EnaNASP proteins in a controlled setting. My data demonstrate that VASP can form hetero-oligomers with itself, Mena, and EVL without bias. However, the assembly of Mena and EVL hetero-tetramers is disfavored. In addition, I find that the tetramerization domain mediates the observed selectivity in complex formation. My findings suggest that hetero-tetramerization serve as an additional method to regulate the activity of EnaNASP proteins.