Eps15 homology (EH) domains are important mediators of protein-protein interactions in various trafficking processes in the cell. EH domains were shown to bind motifs containing the amino acid residues Asn-Pro-Phe (NPF) in unfolded regions of their binding partners (de Beer et al., 1998; Confalonieri and Di Fiore, 2002; Morgan et al., 2003). So far, interactions between EH-domains and their respective ligands were reported to be of low affinity and also low specificity (Salcini et al., 1997).
We discovered a highly specific, high affinity interaction between Eps15, an essential accessory protein during clathrin mediated endocytosis, and its binding partner Stonin2 (see Rumpf et al., 2008). Stonin2 was shown to act as a specific sorting adaptor for the internalization of synaptotagmin and thus to be a regulator of synaptic vesicle recycling (Diril et al., 2006).
Eps15 is a multi-modular protein that comprises 3 EH domains, a coiled-coil region and a low complexity region at its c-terminus that harbors several peptide motifs, shown to interact with other endocytic proteins, for example the AP-2 complex (Figure 1). Stonin2 consists of a ? homology domain, a Stonin homology (SH) domain and a low complexity N-terminus with 2 NPF motifs.
Figure 1: Domain structure of Eps15 and Stonin2