1oiz

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Template:STRUCTURE 1oiz

THE MOLECULAR BASIS OF VITAMIN E RETENTION: STRUCTURE OF HUMAN ALPHA-TOCOPHEROL TRANSFER PROTEIN

Overview

Alpha-tocopherol transfer protein (alpha-TTP) is a liver protein responsible for the selective retention of alpha-tocopherol from dietary vitamin E, which is a mixture of alpha, beta, gamma, and delta-tocopherols and the corresponding tocotrienols. The alpha-TTP-mediated transfer of alpha-tocopherol into nascent VLDL is the major determinant of plasma alpha-tocopherol levels in humans. Mutations in the alpha-TTP gene have been detected in patients suffering from low plasma alpha-tocopherol and ataxia with isolated vitamin E deficiency (AVED). The crystal structure of alpha-TTP reveals two conformations. In its closed tocopherol-charged form, a mobile helical surface segment seals the hydrophobic binding pocket. In the presence of detergents, an open conformation is observed, which probably represents the membrane-bound form. The selectivity of alpha-TTP for RRR-alpha-tocopherol is explained from the van der Waals contacts occurring in the lipid-binding pocket. Mapping the known mutations leading to AVED onto the crystal structure shows that no mutations occur directly in the binding pocket.

About this Structure

1OIZ is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.

Reference

The molecular basis of vitamin E retention: structure of human alpha-tocopherol transfer protein., Meier R, Tomizaki T, Schulze-Briese C, Baumann U, Stocker A, J Mol Biol. 2003 Aug 15;331(3):725-34. PMID:12899840 Page seeded by OCA on Sat May 3 03:54:40 2008