leucine zipper

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leucine zipper A molecular motif, originally discovered in DNA-binding proteins but also found in other proteins, in which a set of four or five consecutive leucine residues is repeated every seven amino acids in the primary sequence. In a helical configuration this produces a line of leucines on one side of the helix. With two such helixes alongside each other, the arrays of leucines can interdigitate like a zip fastener, thus forming a stable link between the two helices.