7el6
Structure of SMCR8 bound FEM1B
Structural highlights
FunctionSMCR8_HUMAN Component of the C9orf72-SMCR8 complex, a complex that has guanine nucleotide exchange factor (GEF) activity and regulates autophagy (PubMed:20562859, PubMed:27193190, PubMed:27103069, PubMed:27559131, PubMed:27617292, PubMed:28195531). In the complex, C9orf72 and SMCR8 probably constitute the catalytic subunits that promote the exchange of GDP to GTP, converting inactive GDP-bound RAB8A and RAB39B into their active GTP-bound form, thereby promoting autophagosome maturation (PubMed:20562859, PubMed:27103069, PubMed:27617292, PubMed:28195531). The C9orf72-SMCR8 complex also acts as a negative regulator of autophagy initiation by interacting with the ATG1/ULK1 kinase complex and inhibiting its protein kinase activity (PubMed:27617292, PubMed:28195531). Acts as a regulator of mTORC1 signaling by promoting phosphorylation of mTORC1 substrates (PubMed:27559131, PubMed:28195531). In addition to its activity in the cytoplasm within the C9orf72-SMCR8 complex, SMCR8 also localizes in the nucleus, where it associates with chromatin and negatively regulates expression of suppresses ULK1 and WIPI2 genes (PubMed:28195531).[1] [2] [3] [4] [5] [6] FEM1B_HUMAN Component of an E3 ubiquitin-protein ligase complex, in which it may act as a substrate recognition subunit. Involved in apoptosis by acting as a death receptor-associated protein that mediates apoptosis. Also involved in glucose homeostasis in pancreatic islet. Functions as an adapter/mediator in replication stress-induced signaling that leads to the activation of CHEK1.[7] [8] Publication Abstract from PubMedC-degrons play critical roles in targeting the receptor proteins of Cullin-RING E3 ligase complexes to initiate protein degradation. FEM1 proteins, including FEM1A, FEM1B, and FEM1C, act as the receptors to specifically recognize Arg/C-degrons to enable CRL2-mediated protein turnover. Very few substrates have been identified for FEM1B, except CDK5R1. We found that CRL2(FEM1B) also recognizes the C-degron of an SMCR8 isoform, and uncovered the recognition of SMCR8 by FEM1B through presenting the structure of FEM1B bound to SMCR8. Our work provides insights into the role of CRL2(FEM1B) in regulating the lifetime of SMCR8, a critical autophagy regulator. Structural insights into SMCR8 C-degron recognition by FEM1B.,Zhao S, Ru W, Chen X, Liao S, Zhu Z, Zhang J, Xu C Biochem Biophys Res Commun. 2021 Jun 11;557:236-239. doi:, 10.1016/j.bbrc.2021.04.046. Epub 2021 Apr 20. PMID:33892462[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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