| Accession: | |
|---|---|
| Functional site class: | FEM1ABC C-terminal Arg degrons |
| Functional site description: | C-degrons play critical roles in targeting the receptor proteins of several cullin-RING E3 ligase complexes (CRLs) to initiate protein degradation. FEM1 proteins, including FEM1A/B/C, act as the receptors to specifically recognize C degrons ending with arginine (Arg/C-degron) to enable CRL2-mediated proteasomal turnover Cul2 ligase complexes, including Cul2FEM1A, Cul2FEM1B, and Cul2FEM1C, are responsible for targeting substrates with arginine as their C-terminal residue (Koren,2018; Lin,2018). Meanwhile some of the known substrates have native C-termini ending in Arg, others are generated through proteolysis. |
| ELMs with same func. site: | DEG_Cend_FEM1AC_1 DEG_Cend_FEM1B_2 |
| ELM Description: | Cul2 ligase complexes, including Cul2FEM1A, Cul2FEM1B, and Cul2FEM1C, are responsible for targeting substrates with arginine as their C-terminal residue (Koren,2018; Lin,2018). The specificities of FEM1A, FEM1B and FEM1C overlap considerably, but they do have marked preferences in their substrates (Chen,2021). FEM1A and FEM1C prefer charged, while FEM1B hydrophobic residues preceding the carboxy-terminal Arg residue (Timms,2020). The degron binding pocket for these substrates involves ankyrin repeats within the FEM1-family substrate adaptors. FEM1A/B/C degrons bind to ankyrin repeats via the C-terminal arginine. In the case of FEM1B binding to CD5R1_HUMAN (7cng), the C-terminal Arg binds with FEM1B via cation-π and hydrogen bonds to a negatively charged pocket. Leu at position -3 interacts with Tyr163 and Phe193. Flanking region also interacts with FEM1B: Gly at position -4 binds to Asn151 though hydrogen binding and to Cys186 and His218 via van de Waals interactions; Leu at position -5/-7 might form hydrogen bonds with Tyr153, Cys186 and His218; Arg at position -8 forms salt bridge with Glu196 (Chen,2021). Highly similar interactions occur when FEM1B binds to SMCR8_HUMAN isoform 2 (7el6): The C-terminal arginine binds to Asp82 and Asp131, while cation- π interactions occur with Phe81 and Phe130 and hydrogen bonds form with Trp93 and Ser122. In addition to binding Tyr163 and Phe193, Leu -3 also binds to Ile160. Gly at position -4 forms van der Waals interaction with Tyr153 and Trp at -8 position interacts with His185 (Zhao,2021). The degron size recognized by FEM1 proteins may be notably larger than other C-degron pathways, as evident from experiments where transplanting the last 25 amino acids was necessary to destabilize a heterologous protein (Lin,2018). |
| Pattern: | .L.R$ |
| Pattern Probability: | 0.0000083 |
| Present in taxon: | Metazoa |
| Interaction Domain: |
Ankyrin repeat (IPR002110)
The ankyrin repeat is one of the most common protein-protein interaction motifs in nature
(Stochiometry: 1 : 1)
|
| Acc., Gene-, Name | Start | End | Subsequence | Logic | #Ev. | Organism | Notes |
|---|---|---|---|---|---|---|---|
| Q8TEV9-2 SMCR8 SMCR8_HUMAN |
784 | 787 | ASSPLHIMDFQKWKLIGLQR | TP | 3 | Homo sapiens (Human) | |
| Q15078 CDK5R1 CD5R1_HUMAN |
304 | 307 | DLKNESGQEDKKRLLLGLDR | TP | 5 | Homo sapiens (Human) |