Answer :
β-barrel
What is the structure of β-barrel proteins?
A beta barrel is a beta sheet made of tandem repetitions that twists and coils to form a closed toroidal structure in protein structures. The first strand of the beta barrel is connected to the last strand (hydrogen bond). Many beta-barrels have an antiparallel arrangement of the beta-strands. The majority of them are proteins that are soluble in water and typically bind hydrophobic ligands in the middle of the barrel, like lipocalins. More than 600 proteins with a variety of functions have been shown to include the beta barrel shape.
In many cases, the strands contain alternating polar and non-polar (hydrophilic and hydrophobic) amino acids. As a result, the polar residues are oriented toward the solvent-exposed surface of the barrel and the hydrophobic residues are oriented into the interior of the barrel to form a hydrophobic core.
I understand the question you are looking for is this:
If a transmembrane domain of protein contains -sheet structure, the overall structure of the transmembrane portion is likely a ____________.
A) β-barrel
B) β-tube
C) β-turn
D) β-helix
E) none of the above
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