<p>Kelch is a 50-residue motif, named after the Drosophila mutant in which it was first identified [<cite idref="PUB00000885"/>]. This sequence motif represents one beta-sheet blade, and several of these repeats can associate to form a beta-propeller. For instance, the motif appears 6 times in Drosophila egg-chamber regulatory protein, creating a 6-bladed beta-propeller. The motif is also found in mouse protein MIPP [<cite idref="PUB00000885"/>] and in a number of poxviruses. In addition, kelch repeats have been recognised in alpha- and beta-scruin [<cite idref="PUB00003094"/>, <cite idref="PUB00003079"/>], and in galactose oxidase from the fungus <taxon tax_id="5132">Dactylium dendroides</taxon> [<cite idref="PUB00003318"/>, <cite idref="PUB00004093"/>]. The structure of galactose oxidase reveals that the repeated sequence corresponds to a 4-stranded anti-parallel beta-sheet motif that forms the repeat unit in a super-barrel structural fold [<cite idref="PUB00003324"/>].</p><p>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 [<cite idref="PUB00003094"/>]. 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 [<cite idref="PUB00003318"/>].</p><p>This entry represents the 6-bladed Kelch beta-propeller, which consists of six 4-stranded beta-sheet motifs (or six Kelch repeats). </p>