InterPro domain: IPR011043

This entry represents a beta-propeller domain found in galactose oxidase and in Kelch repeat-containing proteins.

The known functions of kelch-containing proteins are diverse: scruin is an actin cross-linking protein; galactose oxidase catalyses the oxidation of the hydroxyl group at the C6 position in D-galactose; neuraminidase hydrolyses sialic acid residues from glycoproteins; and kelch may have a cytoskeletal function, as it is localised to the actin-rich ring canals that connect the 15 nurse cells to the developing oocyte in Drosophila [ 1 ]. Nevertheless, based on the location of the kelch pattern in the catalytic unit in galactose oxidase, functionally important residues have been predicted in glyoxal oxidase [ 2 ].

Galactose oxidase ( 1.1.3.9 ) is a monomeric enzyme that contains a single copper ion and catalyses the stereospecific oxidation of primary alcohols to their corresponding aldehyde [ 3 ]. The protein contains an unusual covalent thioether bond between a tyrosine and a cysteine that forms during its maturation [ 4 ]. Galactose oxidase is a three-domain protein: the N-terminal domain forms a jelly-roll sandwich, the central domain forms a seven 4-bladed beta-propeller, and the C-terminal domain has an immunoglobulin-like fold.

1. beta-Scruin, a homologue of the actin crosslinking protein scruin, is localized to the acrosomal vesicle of Limulus sperm. J. Cell. Sci. 108 ( Pt 10), 3155-62
2. Drosophila kelch motif is derived from a common enzyme fold. J. Mol. Biol. 236, 1277-82
3. Crystal structure of the precursor of galactose oxidase: an unusual self-processing enzyme. Proc. Natl. Acad. Sci. U.S.A. 98, 12932-7
4. Galactose oxidase. Adv. Protein Chem. 60, 1-49