InterPro domain: IPR001251

The CRAL-TRIO domain is a protein structural domain that binds small lipophilic molecules [ 1 ]. The domain is named after cellular retinaldehyde-binding protein (CRALBP) and TRIO guanine exchange factor.

The CRAL-TRIO domain is found in GTPase-activating proteins (GAPs), guanine nucleotide exchange factors (GEFs) and a family of hydrophobic ligand binding proteins, including the yeast SEC14 protein and mammalian retinaldehyde- and alpha-tocopherol-binding proteins. The domain may either constitute all of the protein or only part of it [ 2 , 3 , 4 , 5 ].

The structure of the domain in SEC14 proteins has been determined [ 6 ]. The structure contains several alpha helices as well as a beta sheet composed of 6 strands. Strands 2,3,4 and 5 form a parallel beta sheet with strands 1 and 6 being anti-parallel. The structure also identified a hydrophobic binding pocket for lipid binding.

1. Ligand specificity in the CRAL-TRIO protein family. Biochemistry 42, 6467-74
2. Cloning and characterization of Kluyveromyces lactis SEC14, a gene whose product stimulates Golgi secretory function in Saccharomyces cerevisiae. J. Bacteriol. 172, 4510-21
3. Primary structure of alpha-tocopherol transfer protein from rat liver. Homology with cellular retinaldehyde-binding protein. J. Biol. Chem. 268, 17705-10
4. Crystal structure of the Saccharomyces cerevisiae phosphatidylinositol-transfer protein. Nature 391, 506-10
5. A novel human tocopherol-associated protein: cloning, in vitro expression, and characterization. J. Biol. Chem. 275, 25672-80