The putative ZZ zinc finger, was first identified in the Dystrophin gene, a 427 kDa protein, involved in the Duchenne muscular dystrophy (DMD). This motif is also present in the adaptor proteins CBP and P300 in a region known to interact with YY1, E1A and TFIIB, which suggest a possible protein binding function for this domain [1]. It is closely related to the B-box zinc finger, (see <PDOC50119>) however B-box do not contain the Asp-Tyr-Asp-Leu motif present in most of the ZZ zinc fingers [2].

Some of the proteins containing this domain are listed below:

• Mammalian CBP and the related protein p300. Large nuclear proteins that interact with transcriptional activators and repressors.
• Mammalian dystrophin, a multidomain cytoskeletal protein. Its longest alternatively spliced form consists of an N-terminal actin-binding domain, followed by 24 spectrin-like repeats, a cysteine-rich calcium-binding domain and a C-terminal globular domain. Dystrophin form tetramers and is thought to have multiple functions including involvement in membrane stability, transduction of contractile forces to the extracellular environment and organization of membrane specialization. Mutations in the dystrophin gene lead to muscular dystrophy of Duchenne or Becker type.
• Human dystrophin related protein 2. Possibly involved in membrane- cytosqueleton interactions in the central nervous system.
• Utrophin, a dystrophin-like protein of unknown function.
• Drosophila Ref(2)P protein. Implicated in sigma rhabdovirus multiplication and necessary for male fertility.
• Prt1 of Arabidopsis thaliana. Encodes a component of the plant N-end rule pathway [3].

The ZZ zinc finger contains 7 positions able to coordinate one zinc atom, among them only 4 are completely conserved. Our pattern is based on these 4 positions. We have also developed a profile that spans the whole domain.

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