1em2
From Proteopedia
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STAR-RELATED LIPID TRANSPORT DOMAIN OF MLN64
Overview
The steroidogenic acute regulatory protein (StAR) regulates acute, steroidogenesis in the adrenal cortex and gonads by promoting the, translocation of cholesterol to the mitochondrial inner membrane where the, first step in steriod biosynthesis is catalyzed. StAR-related lipid, transfer (START) domains occur in proteins involved in lipid transport and, metabolism, signal transduction, and transcriptional regulation. The 2.2 A, resolution crystal structure of the START domain of human MLN64 reported, here reveals an alpha/beta fold built around a U-shaped incomplete, beta-barrel. The interior of the protein encompasses a 26 x 12 x 11 A, hydrophobic tunnel that is large enough to bind a single cholesterol, molecule. The StAR and MLN64 START domains bind 1 mole of 14C cholesterol, per mole of protein in vitro. Based on the START domain structure and, cholesterol binding stoichiometry, it is proposed that StAR acts by, shuttling cholesterol molecules one at a time through the intermembrane, space of the mitochondrion.
About this Structure
1EM2 is a Single protein structure of sequence from Homo sapiens with TAR as ligand. Full crystallographic information is available from OCA.
Reference
Structure and lipid transport mechanism of a StAR-related domain., Tsujishita Y, Hurley JH, Nat Struct Biol. 2000 May;7(5):408-14. PMID:10802740
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