The epsin NH2-terminal homology (ENTH) domain is a membrane interacting module of ~140 amino acids. Typically it is located within 20 residues of the NH2-terminus of proteins that often contain consensus sequences for binding to clathrin coat components and their accessory factors, and therefore function as endocytic adaptors. ENTH domain containing proteins have additional roles in signaling and actin regulation and may have yet other actions in the nucleus. The ENTH domain is found associated with other domains such as UIM (see <PDOC50330>), the EH domain binding motif NPF, the DPW/F motif or the I/LWEQ domain. The ENTH domain has been shown to bind to phosphoinositides, as well as to interact with proteins, such as the transcription factor PLZF and tubulin [1,2,3,4].

The ENTH domain forms a compact globular structure, composed of eight α-helices connected by loops of varying length (see <PDB:1EDU>). The general topology of the domain is determined by three helical hairpins that are stacked consecutively with a right handed twist. The most highly conserved amino acids fall roughly into two classes: (i) internal residues that are involved in packing and therefore are necessary for structural integrity, and (ii) solvent accessible residues that may be involved in protein-protein interactions. The ENTH domain is structurally similar to the VHS domain (see <PDOC50179>) [4,5].

Some proteins known to contain a ENTH domain are listed below:

• Mammalian epsin 1, 2 and 3 and their yeast homologs Ent1 through Ent4.
• Drosophila liquid facets (LqF), an epsin ortholog.
• Mammalian AP180, a third major component of neuronal endocytic clathrin coats besides clathrin and AP-2.
• Mammalian CALM, the non-neuronal homolog of AP180.
• Yeast yAP180A and yAP180B, two AP180 homologs.
• Mammalian HIP1 and HIP1R. so called because of their property to interact with huntingtin (huntingtin interacting protein and huntingtin interacting protein related, respectively), the Huntington disease protein.
• Yeast Sla2, the homolog of HIP1/HIP1R.

The profile we developed spans the entire ENTH domain.