Protein Degradation: RING Domain

Domain Binding and Function

The RING finger is a specialized type of Znfinger consisting of 40–60 residues that binds two atoms of zinc, and is involved in mediating protein—protein interactions. The presence of a RING finger domain is a characteristic of RING-class E3 ubiquitin protein ligases capable of transfering ubiquitin from an E2 enzyme to a substrate protein. The RING domain mediates the interaction with the appropriate E2 enzyme. Unlike HECT E3s that form a thioester with ubiquitin, RING fingers likely mediate ubiquitination by facilitating the direct transfer of ubiquitin from E2s to lysine residues on the target substrate. RING finger proteins include the Hrt1/Roc1/Rbx1 proteins found in both the SCF and VCB-like E3 complexes, the APC1 component of the Anaphase Promoting Complex, Cbl family proteins, MDM2 and many other proteins with demonstrated E3 activity, E2 binding or involvement in ubiquitination. In addition to the involvement of RING finger domains in ubiquitin transfer, this domain has also been associated with certain transcription factors such as TIF1β, the PML-family, NFX1 and XPRF.

Structure Reference

1. Zheng, N. et al. (2000) Cell 102(4), 533–539.E

Examples of Domain Proteins

Binding Examples

RING Domain Proteins	Binding Partners
Cbl	UbcH7
RAD5	UBC13-MMS2 complex
RAD6	RAD18
HHARI	UbcH7