Example of an immunoglobulin domain, the fibronectin type III domain from human tenascin (PDB accesion code 1TEN), colored from blue (N-terminus) to red (C-terminus).

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. Image File history File links Download high resolution version (720x1146, 248 KB) Summary Fibronectin type III domain from human tenascin (example of immunoglobulin domain). ... Image File history File links Download high resolution version (720x1146, 248 KB) Summary Fibronectin type III domain from human tenascin (example of immunoglobulin domain). ... An all-β protein fold is a class of structural domains in which the secondary structure is composed entirely of β-sheets, with the possible exception of a few isolated α-helices on the periphery. ... Diagram of Î’-Pleated sheet and bond structure of protein The β sheet (also β-pleated sheet) is a commonly occurring form of regular secondary structure in proteins, first proposed by Linus Pauling and Robert Corey in 1951. ... Diagram of Î’-Pleated sheet and bond structure of protein The β sheet (also β-pleated sheet) is a commonly occurring form of regular secondary structure in proteins, first proposed by Linus Pauling and Robert Corey in 1951. ...

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.

External links

• SCOP listing of immunoglobulin domains of known structure