protein K63-linked ubiquitination

Definition

Target type: biologicalprocess

A protein ubiquitination process in which a polymer of ubiquitin, formed by linkages between lysine residues at position 63 of the ubiquitin monomers, is added to a protein. K63-linked ubiquitination does not target the substrate protein for degradation, but is involved in several pathways, notably as a signal to promote error-free DNA postreplication repair. [GOC:mah, PMID:15556404]

K63-linked ubiquitination is a crucial post-translational modification that plays a critical role in diverse cellular processes. Unlike K48-linked ubiquitination, which primarily targets proteins for degradation by the proteasome, K63-linked ubiquitination does not lead to protein degradation. Instead, it serves as a versatile signaling mechanism involved in various cellular functions, including DNA repair, signal transduction, and immune responses.

The process of K63-linked ubiquitination begins with the activation of ubiquitin by the E1 ubiquitin-activating enzyme. The activated ubiquitin is then transferred to an E2 ubiquitin-conjugating enzyme, which facilitates the attachment of ubiquitin to a target protein. This process is further regulated by E3 ubiquitin ligases, which recognize specific target proteins and recruit the E2 enzyme to the site of ubiquitination.

K63-linked ubiquitination involves the formation of polyubiquitin chains, where ubiquitin monomers are linked together via lysine residue 63. This distinct linkage pattern results in a branched, non-degradative ubiquitin chain that acts as a scaffold for the recruitment of downstream effector proteins.

During DNA repair, K63-linked ubiquitination plays a critical role in the assembly of repair complexes. It facilitates the recruitment of DNA repair proteins, such as BRCA1 and 53BP1, to sites of DNA damage, enabling efficient DNA repair.

In signal transduction, K63-linked ubiquitination often acts as a signal amplifier. It enhances the activity of signaling proteins by promoting their interactions with other proteins, thereby amplifying the signal downstream.

K63-linked ubiquitination is also crucial for immune responses. It regulates the activation and signaling of immune receptors, such as Toll-like receptors (TLRs). It also plays a role in the formation of signaling complexes that mediate the production of inflammatory cytokines.

In summary, K63-linked ubiquitination is a complex and dynamic process that serves as a versatile signaling mechanism in various cellular processes. Its unique non-degradative nature allows it to regulate diverse cellular functions, including DNA repair, signal transduction, and immune responses.'
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Proteins (3)

Compounds (15)