The E3 ligases are responsible for substrate specificity of the ubiquitin proteasome system. E3 ligases consist of a single protein (= HECT-domain E3-ligases) or a protein complex (i.e. RING finger containing E3s) able to bind to the substrate and to interact with the E2 conjugating enzyme. The interaction between E3-ligase and substrate is either direct or via an ancillary protein. The protein substrates are specified for ubiquitination by special recognition signals. |
