Geranylgeranylation

Geranylgeranylation
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Geranylgeranylation is a form of prenylation, a post-translational modification of proteins. This process involves the addition of a geranylgeranyl group to a cysteine residue at or near the C-terminus of a protein. Geranylgeranylation is crucial for the proper functioning of a variety of proteins, including members of the Rho family of GTPases, which are involved in cell signaling and cytoskeletal dynamics.

Mechanism

Geranylgeranylation is catalyzed by the enzyme geranylgeranyltransferase. This enzyme transfers a geranylgeranyl moiety from geranylgeranyl pyrophosphate (GGPP) to the target protein. The modification typically occurs at a CAAX motif, where "C" is a cysteine, "A" is an aliphatic amino acid, and "X" is any amino acid that determines the type of prenylation.

Biological Significance

The addition of a geranylgeranyl group increases the hydrophobicity of the protein, facilitating its association with cell membranes. This membrane association is essential for the protein's biological activity. For example, geranylgeranylation of Rho GTPases is necessary for their role in regulating the actin cytoskeleton, which is important for cell migration, cell division, and cell shape.

Clinical Implications

Defects in geranylgeranylation can lead to various diseases. For instance, improper prenylation of proteins has been implicated in certain cancers and cardiovascular diseases. Inhibitors of geranylgeranyltransferase are being explored as potential therapeutic agents for these conditions.

See Also

• Prenylation
• Farnesylation
• Protein modification

References

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External Links

• [Geranylgeranylation on Wikipedia](https://en.wikipedia.org/wiki/Geranylgeranylation)