InterPro domain: IPR042044

Subunits of the vesicle tethering complex (such as Tip20 and Dsl1) share protein sequence similarity with known subunits of the exocyst complex, establishing a structural connection among several multi-subunit tethering complexes and implying that many of their subunits are derived from a common progenitor.

Proteins containing this domain includes EXOC6/PINT-1 from animals, Tip20 from budding yeast, Sec15 from fission yeasts and MAIGO2 (Mag2) from plants. Sec15 (EXOC6 homologue) is an exocyst complex component that links Sec4 and downstream fusion effectors at discrete cellular locations. Its C-terminal domain mediates Rab GTPases binding which occurs in a GTP-dependent manner [ 1 ]. PINT-1/Tip20/MAIGO2 play a role in anterograde transport from the endoplasmic reticulum (ER) to the Golgi and/or retrograde transport from the Golgi to the ER. They share a similar domain organisation with an N-terminal leucine heptad repeat rich coiled coil and an ~500-residue C-terminal RINT1/TIP20 domain, which might be a protein-protein interaction module necessary for the formation of functional complexes.

This superfamily represents a subdomain known as domain D found at the C terminus of Tip20, which is part of the Dsl1p vesicle tethering complex essential for trafficking from the Golgi apparatus to the ER. The structure of Tip20p consists entirely of alpha-helices and intervening loops of variable length, organised into a series of helix bundle domains [ 2 ].

1. Sec15 interacts with Rab11 via a novel domain and affects Rab11 localization in vivo. Nat. Struct. Mol. Biol. 12, 879-85
2. Structural characterization of Tip20p and Dsl1p, subunits of the Dsl1p vesicle tethering complex. Nat. Struct. Mol. Biol. 16, 114-23