Immunoglobulin fold



An immunoglobulin fold is a common all-β protein fold that consists of a 2-layer sandwich of ~7 antiparallel β-strands arranged in two β-sheets.

The backbone switches repeatedly between the two β-sheets. Typically, the pattern is (N-terminal β-hairpin in sheet 1)-(β-hairpin in sheet 2)-(β-strand in sheet 1)-(C-terminal β-hairpin in sheet 2). The cross-overs between sheets form an "X", so that the N- and C-terminal hairpins are facing each other.