InterPro domain: IPR035802

Tepsin (also known as the product of the ENTHD2 or AP4AT gene) is an AP-4 accessory protein. It binds to the beta4-ear domain of AP-4, and is recruited to the trans-Golgi network (TGN) in manner dependent on this interaction [ 1 ]. This is the ENTH/VHS domain in tepsin and in A. thaliana protein At3g16270 [ 2 ].

Unlike the other members of the ENTH/ANTH/VHS superfamily, the tepsin ENTH domain lacks helix0, helix8, and a lipid binding pocket. Loss of helix0 precludes formation of a lipid binding pocket and explains why tepsin ENTH domain cannot interact directly with phosphoinositide head groups [ 3 ].

1. Bivalent Motif-Ear Interactions Mediate the Association of the Accessory Protein Tepsin with the AP-4 Adaptor Complex. J. Biol. Chem. 290, 30736-49
2. NMR assignment of the hypothetical ENTH-VHS domain At3g16270 from Arabidopsis thaliana. J. Biomol. NMR 29, 205-6
3. Structure and evolution of ENTH and VHS/ENTH-like domains in tepsin. Traffic