Beta trefoil fold
In
beta strands. Together these form a beta barrel with a triangular "cap", each consisting of three hairpins. Overall, this structure has an approximate three-fold symmetry.[1][2]
Details
The hairpins are arranged in three
β sequences, each having a "Y" or trefoil-like structure. The first and fourth β strands form one hairpin, while the second and third form the other hairpin- each hairpin forms another arm of the "Y" and the long loop forms its trunk.[1][2]
The beta barrel has a 16
Å diameter, and is filled with amino acid
side-chains.
[1]
Occurrence
Among other proteins, β trefoil fold is found in