ABCE1 is a highly conserved cytosolic Fe-S ABC-family ATPase that drives eukaryotic ribosome recycling. After canonical termination, or after PELO/HBS1L recognition of stalled or vacant ribosomes, ABCE1 uses ATP hydrolysis to split 80S ribosomes into 60S and 40S subunits, thereby coupling translational termination, ribosome-associated quality control, and re-use of ribosomal subunits. ABCE1 contains an N-terminal 4Fe-4S cluster binding region and two ABC nucleotide-binding domains. It was originally identified as RNase L inhibitor/RLI and can inhibit the 2-5A/RNASEL pathway, but current biochemical and genetic evidence supports ribosome recycling as its core conserved function.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005829 cytosol | IBA GO_REF:0000033 | ACCEPT | Summary: ABCE1 is a conserved cytosolic ribosome-recycling ATPase. Cytosolic localization is consistent with the experimentally supported cytoplasmic localization and its activity on cytosolic 80S ribosomes. Reason: The annotation captures the main compartment where ABCE1 carries out its core function on cytosolic ribosomes. Supporting Evidence: PMID:20122402 ABCE1 dissociates post-TCs into free 60S subunits and mRNA- and tRNA-bound 40S subunits. |
| GO:0006415 translational termination | IBA GO_REF:0000033 | ACCEPT | Summary: ABCE1 acts at the post-termination stage of translation, after release factor action, to recycle post-termination ribosomes. Reason: Although the most precise process term for ABCE1 is ribosome disassembly, post-termination ribosome recycling is mechanistically part of the termination-to-reinitiation transition and is well supported for ABCE1. Supporting Evidence: PMID:20122402 After termination, eukaryotic 80S ribosomes remain associated with mRNA, P-site deacylated tRNA, and release factor eRF1 and must be recycled by dissociating these ligands and separating ribosomes into subunits. |
| GO:0005506 iron ion binding | IBA GO_REF:0000033 | MODIFY | Summary: ABCE1 contains a conserved N-terminal iron-sulfur cluster binding region. The generic "iron ion binding" term is directionally correct but less precise than the 4Fe-4S cluster binding term. Reason: UniProt and the deep research report both describe an N-terminal Fe-S domain required for ABCE1 function. The more informative GO term is 4 iron, 4 sulfur cluster binding. Proposed replacements: 4 iron, 4 sulfur cluster binding Supporting Evidence: PMID:20122402 ABCE1 comprises an N-terminal domain harboring two [4Fe-4S] clusters that is structurally related to bacterial-type ferredoxins, followed by two NBDs arranged by a hinge domain (Karcher et al., 2008). file:human/ABCE1/ABCE1-deep-research-falcon.md ABCE1 (ATP-binding cassette subfamily E member 1; also historically **RNase L inhibitor/RLI**) is an essential, highly conserved **Fe–S ABC-family ATPase** that acts as the principal **eukaryotic ribosome recycling (splitting) factor**. file:human/ABCE1/ABCE1-bioinformatics/RESULTS.md The N-terminal region (residues 1-80) contains nine cysteines arranged across the two UniProt-annotated 4Fe-4S ferredoxin-type domains (7-37 and 46-75), consistent with coordination of two [4Fe-4S] clusters rather than mononuclear iron. |
| GO:0005524 ATP binding | IBA GO_REF:0000033 | ACCEPT | Summary: ABCE1 has two ABC nucleotide-binding domains with predicted ATP-binding sites and experimentally supported ATP-dependent ribosome recycling. Reason: ATP binding is an integral molecular property of the ABCE1 ATPase cycle that drives ribosome splitting. Supporting Evidence: PMID:20122402 NTP hydrolysis by ABCE1 is stimulated by post-TCs and is required for its recycling activity. |
| GO:0006413 translational initiation | IBA GO_REF:0000033 | MARK AS OVER ANNOTATED | Summary: ABCE1 promotes ribosome recycling, which enables ribosomal subunits to be reused for subsequent initiation, but it is not itself a canonical translation initiation factor. Reason: The evidence supports an indirect effect on initiation through ribosome recycling and 40S reuse. Ribosome disassembly and rescue of stalled cytosolic ribosomes are more accurate process annotations for ABCE1. Supporting Evidence: PMID:20122402 ABCE1 dissociates post-TCs into free 60S subunits and mRNA- and tRNA-bound 40S subunits. |
| GO:0043024 ribosomal small subunit binding | IBA GO_REF:0000033 | ACCEPT | Summary: ABCE1 associates with ribosomal subunits during recycling and is reported to remain with the 40S subunit after splitting in structural and pathway models. Reason: Small ribosomal subunit binding is consistent with ABCE1's core ribosome-recycling mechanism. Supporting Evidence: PMID:20122402 we observed that in the AMPPNP-bound form, ABCE1 efficiently associated with 40S subunits and 43S complexes |
| GO:0005515 protein binding | IPI PMID:16275648 Basic residues in the nucleocapsid domain of Gag are require... | REMOVE | Summary: This annotation reflects interaction with HIV-1 Gag during viral capsid assembly. Reason: Protein binding is too generic to represent ABCE1 function, and the specific viral Gag interaction is a host-virus interaction rather than a core human gene-product function. Supporting Evidence: PMID:16275648 In primate cells, ABCE1 associates with Gag polypeptides present in immature capsid assembly intermediates. |
| GO:0005515 protein binding | IPI PMID:25944354 Host interactions of Chandipura virus matrix protein. | REMOVE | Summary: This annotation reflects a Chandipura virus matrix protein interaction from a host-interactor screen. Reason: Generic protein binding is not informative for ABCE1's molecular function, and a viral matrix protein interaction should not drive the core GO molecular-function model for human ABCE1. Supporting Evidence: PMID:25944354 The present study aims to screen the human fetal brain cDNA library for interactors of CHPV M protein using yeast two-hybrid system. |
| GO:0005515 protein binding | IPI PMID:32296183 A reference map of the human binary protein interactome. | REMOVE | Summary: This high-throughput binary interactome annotation reports protein interaction evidence but does not specify an ABCE1 molecular function. Reason: The term "protein binding" is too broad for curation and does not improve the ABCE1 functional model beyond the specific ribosome-recycling and RNase L inhibitor annotations. Supporting Evidence: PMID:32296183 The dataset, versioned HI-III-20 (Human Interactome obtained from screening Space III, published in 2020), contains 52,569 verified PPIs involving 8,275 proteins (Supplementary Table 9). |
| GO:0005515 protein binding | IPI PMID:35271311 OpenCell: Endogenous tagging for the cartography of human ce... | REMOVE | Summary: This annotation comes from a high-throughput endogenous tagging and cellular organization resource. Reason: Generic protein binding is not an informative molecular function for ABCE1. Specific activities and process terms better represent the supported biology. Supporting Evidence: PMID:35271311 We combined genome engineering, confocal live-cell imaging, mass spectrometry, and data science to systematically map the localization and interactions of human proteins. |
| GO:0005524 ATP binding | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro-based ATP binding is consistent with the two ABC nucleotide-binding domains and the experimentally supported ATPase function of ABCE1. Reason: ATP binding is a required component of ABCE1's ATP hydrolysis-driven ribosome recycling mechanism. Supporting Evidence: PMID:20122402 It can hydrolyze ATP, GTP, UTP, and CTP. |
| GO:0005737 cytoplasm | IEA GO_REF:0000120 | ACCEPT | Summary: Cytoplasmic localization is supported by UniProt and by ABCE1's activity on cytosolic ribosomes. Reason: The annotation is broad but correct; more specific cytosol and cytosolic ribosome annotations are also present. Supporting Evidence: Reactome:R-HSA-8985201 ATP-binding cassette sub-family E member 1 (ABCE1, aka RNase L inhibitor, RLI) is a member of the ATP-binding cassette transporters which express in the cytoplasm and the nuclear membrane. |
| GO:0005739 mitochondrion | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: A mitochondrial fraction of ABCE1/RLI has been reported, and later work links ABCE1 to mitochondrial outer membrane-associated translation quality control under damage conditions. Reason: Mitochondrial association is supported but is not the dominant core function of ABCE1; the core conserved function is cytosolic ribosome recycling. Supporting Evidence: PMID:11585831 We found that a fraction of cellular RNase L and RLI is localized in the mitochondria. PMID:29861391 Mitochondrial damage causes stalled translation of complex-I 30 kDa subunit (C-I30) mRNA on MOM, triggering the recruitment of co-translational quality control factors Pelo, ABCE1, and NOT4 to the ribosome/mRNA-ribonucleoprotein complex. |
| GO:0006412 translation | IEA GO_REF:0000117 | MARK AS OVER ANNOTATED | Summary: ABCE1 is clearly involved in translation, but this broad term obscures the supported mechanism: ATP-driven recycling and splitting of post-termination or stalled cytosolic ribosomes. Reason: The annotation is not wrong, but ribosome disassembly, translational termination, and rescue of stalled cytosolic ribosome are more precise and already present. Supporting Evidence: PMID:20122402 Consistently, we found that silencing of ABCE1 in HeLa cells impaired ribosomal recycling. |
| GO:0016887 ATP hydrolysis activity | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro-based ATPase prediction agrees with direct biochemical evidence that ABCE1 hydrolyzes ATP and requires NTP hydrolysis for recycling. Reason: ATP hydrolysis is the core molecular activity that powers ABCE1-mediated ribosome splitting. Supporting Evidence: PMID:20122402 NTP hydrolysis by ABCE1 is stimulated by post-TCs and is required for its recycling activity. |
| GO:0005829 cytosol | IDA GO_REF:0000052 | ACCEPT | Summary: HPA immunofluorescence supports cytosolic localization, consistent with ABCE1's cytosolic ribosome-recycling role. Reason: This directly supports the main compartment for ABCE1 function. Supporting Evidence: Reactome:R-HSA-8985201 ATP-binding cassette sub-family E member 1 (ABCE1, aka RNase L inhibitor, RLI) is a member of the ATP-binding cassette transporters which express in the cytoplasm and the nuclear membrane. |
| GO:0072344 rescue of stalled cytosolic ribosome | TAS Reactome:R-HSA-9948299 | ACCEPT | Summary: Reactome places ABCE1 downstream of PELO/HBS1L in rescue of non-stop or stalled cytosolic ribosomes, where ABCE1 hydrolyzes ATP to split the 80S ribosome. Reason: This is a core ABCE1 process in ribosome-associated quality control. Supporting Evidence: Reactome:R-HSA-9948299 HBS1L hydrolyzes GTP and dissociates from PELO and the ribosome, exposing a site on PELO to which ABCE1 binds. PMID:21448132 Pelota/Hbs1 also induced dissociation of ECs and release of peptidyl-tRNA, but only in the presence of ABCE1. |
| GO:0016887 ATP hydrolysis activity | TAS Reactome:R-HSA-9955731 | ACCEPT | Summary: Reactome explicitly describes ABCE1 hydrolyzing ATP while bound with PELO to split a stalled 80S ribosome. Reason: ATP hydrolysis is the mechanistic molecular activity driving ABCE1's core ribosome-splitting function. Supporting Evidence: Reactome:R-HSA-9955731 ABCE1 bound to PELO near the P site of the 80S ribosome hydrolyzes ATP, causing dissociation of the 80S ribosome into 40S and 60S ribosomal subunits |
| GO:0006415 translational termination | IDA PMID:20122402 The role of ABCE1 in eukaryotic posttermination ribosomal re... | ACCEPT | Summary: ABCE1 acts on post-termination ribosomal complexes after eRF-mediated peptide release and promotes their recycling. Reason: Direct biochemical evidence supports ABCE1 function at the termination/recycling stage of translation. Ribosome disassembly is the most precise process term, but this termination annotation is defensible. Supporting Evidence: PMID:20122402 ABCE1 dissociates post-TCs into free 60S subunits and mRNA- and tRNA-bound 40S subunits. |
| GO:0017111 ribonucleoside triphosphate phosphatase activity | IDA PMID:20122402 The role of ABCE1 in eukaryotic posttermination ribosomal re... | ACCEPT | Summary: ABCE1 was directly shown to hydrolyze ATP, GTP, UTP and CTP in vitro. Reason: This broad NTPase activity is experimentally supported. For the core cellular mechanism, ATP hydrolysis activity is the more specific and more central molecular function. Supporting Evidence: PMID:20122402 It can hydrolyze ATP, GTP, UTP, and CTP. |
| GO:0022626 cytosolic ribosome | IDA PMID:20122402 The role of ABCE1 in eukaryotic posttermination ribosomal re... | ACCEPT | Summary: ABCE1 acts directly on eukaryotic cytosolic 80S ribosomal complexes and their post-recycling subunits. Reason: The cytosolic ribosome is the active site of ABCE1's core function. Supporting Evidence: PMID:20122402 ABCE1 dissociates post-TCs into free 60S subunits and mRNA- and tRNA-bound 40S subunits. |
| GO:0022626 cytosolic ribosome | IDA PMID:21448132 Dissociation by Pelota, Hbs1 and ABCE1 of mammalian vacant 8... | ACCEPT | Summary: Mammalian ABCE1 functions on vacant and stalled 80S ribosomes with Pelota/Hbs1. Reason: This annotation accurately captures the ribosomal location of ABCE1's stalled-ribosome rescue function. Supporting Evidence: PMID:21448132 Pelota/Hbs1 also induced dissociation of ECs and release of peptidyl-tRNA, but only in the presence of ABCE1. |
| GO:0003924 GTPase activity | IDA PMID:20122402 The role of ABCE1 in eukaryotic posttermination ribosomal re... | KEEP AS NON CORE | Summary: ABCE1 hydrolyzed GTP in vitro in the same biochemical study that established its NTPase activity. Reason: The direct assay supports GTP hydrolysis, but the primary cellular ribosome-recycling mechanism is best represented by ATP hydrolysis activity. Supporting Evidence: PMID:20122402 It can hydrolyze ATP, GTP, UTP, and CTP. |
| GO:0016887 ATP hydrolysis activity | IDA PMID:20122402 The role of ABCE1 in eukaryotic posttermination ribosomal re... | ACCEPT | Summary: ABCE1 directly hydrolyzes ATP, and NTP hydrolysis is required for ribosome recycling. Reason: ATP hydrolysis is the core ABCE1 molecular function that powers 80S ribosome splitting. Supporting Evidence: PMID:20122402 NTP hydrolysis by ABCE1 is stimulated by post-TCs and is required for its recycling activity. |
| GO:0032790 ribosome disassembly | IDA PMID:20122402 The role of ABCE1 in eukaryotic posttermination ribosomal re... | ACCEPT | Summary: ABCE1 dissociates post-termination ribosomes into 60S and 40S subunits in a reconstituted eukaryotic system. Reason: This is the most precise core biological-process annotation for ABCE1's canonical function. Supporting Evidence: PMID:20122402 ABCE1, a conserved and essential member of the ATP-binding cassette (ABC) family of proteins, promotes eukaryotic ribosomal recycling over a wide range of Mg(2+) concentrations. |
| GO:0032790 ribosome disassembly | IDA PMID:21448132 Dissociation by Pelota, Hbs1 and ABCE1 of mammalian vacant 8... | ACCEPT | Summary: ABCE1, with Pelota and Hbs1, dissociates mammalian vacant 80S ribosomes and stalled elongation complexes. Reason: This annotation captures ABCE1's ribosome-splitting role in quality control as well as in recycling. Supporting Evidence: PMID:21448132 Pelota/Hbs1 also induced dissociation of ECs and release of peptidyl-tRNA, but only in the presence of ABCE1. |
| GO:0043273 CTPase activity | IDA PMID:20122402 The role of ABCE1 in eukaryotic posttermination ribosomal re... | KEEP AS NON CORE | Summary: ABCE1 hydrolyzed CTP in vitro in the biochemical study that characterized its broad NTPase activity. Reason: The assay supports CTP hydrolysis, but current evidence for ABCE1's physiological core function points to ATP-driven ribosome recycling. Supporting Evidence: PMID:20122402 It can hydrolyze ATP, GTP, UTP, and CTP. |
| GO:0072344 rescue of stalled cytosolic ribosome | IDA PMID:21448132 Dissociation by Pelota, Hbs1 and ABCE1 of mammalian vacant 8... | ACCEPT | Summary: Mammalian ABCE1 is essential with Pelota, and Hbs1 is stimulatory, for dissociation of stalled elongation complexes in vitro. Reason: This is a core quality-control role for ABCE1 that follows directly from the experimental evidence. Supporting Evidence: PMID:21448132 Whereas Pelota and ABCE1 were essential, Hbs1 had a stimulatory effect. |
| GO:0006515 protein quality control for misfolded or incompletely synthesized proteins | IC PMID:21448132 Dissociation by Pelota, Hbs1 and ABCE1 of mammalian vacant 8... | NEW | Summary: NEW annotation supported by ribosome-associated quality-control pathway context and by direct evidence that mammalian ABCE1, with Pelota/Hbs1, dissociates stalled elongation complexes and releases peptidyl-tRNA. Reason: This broad protein-quality-control term is appropriate as a parent/context process for ABCE1's stalled-ribosome rescue role. It should not replace the more precise core annotations to rescue of stalled cytosolic ribosome and ribosome disassembly. Supporting Evidence: PMID:21448132 Pelota/Hbs1 also induced dissociation of ECs and release of peptidyl-tRNA, but only in the presence of ABCE1. PMID:21448132 Whereas Pelota and ABCE1 were essential, Hbs1 had a stimulatory effect. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-8985201 | ACCEPT | Summary: Reactome's RNASEL binding event places ABCE1/RLI in the cytoplasm and describes its RNase L inhibitory role. Reason: Cytosolic localization is supported and consistent with ABCE1's core ribosome function and non-core RNASEL inhibition function. Supporting Evidence: Reactome:R-HSA-8985201 ATP-binding cassette sub-family E member 1 (ABCE1, aka RNase L inhibitor, RLI) is a member of the ATP-binding cassette transporters which express in the cytoplasm and the nuclear membrane. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-9954919 | ACCEPT | Summary: Reactome describes the cytosolic stalled-ribosome rescue pathway in which HBS1L dissociation exposes PELO for ABCE1 binding. Reason: This is consistent with ABCE1's cytosolic ribosome-associated function. Supporting Evidence: Reactome:R-HSA-9954919 The dissociation exposes a surface on PELO for ABCE1 to bind and allows the central domain of PELO to move towards the peptidyl-tRNA in P site of the 80S ribosome |
| GO:0005829 cytosol | TAS Reactome:R-HSA-9955731 | ACCEPT | Summary: Reactome describes ABCE1-bound PELO hydrolyzing ATP to dissociate a stalled cytosolic 80S ribosome. Reason: The pathway event is cytosolic and mechanistically aligned with ABCE1's core function. Supporting Evidence: Reactome:R-HSA-9955731 ABCE1 bound to PELO near the P site of the 80S ribosome hydrolyzes ATP, causing dissociation of the 80S ribosome into 40S and 60S ribosomal subunits |
| GO:0005515 protein binding | IPI PMID:7539425 Cloning and characterization of a RNase L inhibitor. A new c... | REMOVE | Summary: This annotation reflects ABCE1/RLI association with RNase L. Reason: The RNase L interaction is real, but generic protein binding is not informative. The same evidence is better captured by the specific endoribonuclease inhibitor activity and negative regulation of endoribonuclease activity annotations. Supporting Evidence: PMID:7539425 Its expression in reticulocyte extracts antagonizes the 2-5A binding ability and the nuclease activity of endogenous RNase L or the cloned 2DR polypeptide. |
| GO:0060698 endoribonuclease inhibitor activity | IDA PMID:7539425 Cloning and characterization of a RNase L inhibitor. A new c... | KEEP AS NON CORE | Summary: ABCE1/RLI directly inhibits RNase L activity in the 2-5A/RNase L pathway. Reason: This is a specific, experimentally supported molecular activity, but it appears secondary to ABCE1's conserved core role in ribosome recycling. Supporting Evidence: PMID:7539425 Its expression in reticulocyte extracts antagonizes the 2-5A binding ability and the nuclease activity of endogenous RNase L or the cloned 2DR polypeptide. Reactome:R-HSA-5223305 ATP-binding cassette sub-family E member 1 (ABCE1, aka RNase L inhibitor, RLI) directly interacts with RNASEL and inhibits its endoribonuclease activity |
| GO:0060702 negative regulation of endoribonuclease activity | IDA PMID:7539425 Cloning and characterization of a RNase L inhibitor. A new c... | KEEP AS NON CORE | Summary: ABCE1/RLI negatively regulates RNase L endoribonuclease activity in the interferon-regulated 2-5A pathway. Reason: This regulation is supported experimentally, but it is not the main conserved ABCE1 function relative to ATP-driven ribosome recycling. Supporting Evidence: PMID:7539425 The overexpression of RLI in stably transfected HeLa cells inhibits the antiviral activity of IFN on encephalomyocarditis virus but not on vesicular stomatitis virus. |
| GO:0016020 membrane | HDA PMID:19946888 Defining the membrane proteome of NK cells. | REMOVE | Summary: This high-throughput NK cell membrane-proteome study identified many proteins, including species likely to be transiently or indirectly associated with membranes. Reason: ABCE1 lacks a transmembrane region and its core function is soluble cytosolic ribosome recycling. This broad membrane annotation is weak and likely reflects fractionation or transient association rather than a defining localization. Supporting Evidence: PMID:19946888 The remaining species were largely involved in cellular processes and molecular functions that could be predicted to be transiently associated with membranes. file:human/ABCE1/ABCE1-bioinformatics/RESULTS.md The curated UniProt feature table for P61221 lists zero TRANSMEM features, and an independent Kyte-Doolittle scan (window 19) finds no window reaching the 1.6 transmembrane-helix threshold (global maximum 1.54 at residue 64), confirming ABCE1 has no transmembrane region and is a soluble cytosolic protein. file:human/ABCE1/ABCE1-hypotheses/function-hypothesis-go-0016020/openscientist.md The GO:0016020 annotation is over-annotated and should be removed. |
| GO:0005759 mitochondrial matrix | TAS Reactome:R-HSA-5223305 | MODIFY | Summary: Mitochondrial association of ABCE1/RLI is supported, but the more specific mitochondrial matrix location is not clearly justified by the cited RNASEL inhibition event. Reason: The available evidence supports mitochondrion-level association, not a confidently matrix-specific localization. Use the broader mitochondrion term. Proposed replacements: mitochondrion Supporting Evidence: PMID:11585831 We found that a fraction of cellular RNase L and RLI is localized in the mitochondria. |
| GO:0005737 cytoplasm | IDA PMID:11585831 The 2-5A/RNase L/RNase L inhibitor (RLI) [correction of (RNI... | ACCEPT | Summary: The interferon/RNase L study supports cellular ABCE1/RLI localization in cytoplasm with an additional mitochondrial fraction. Reason: Cytoplasmic localization is well aligned with ABCE1's ribosome-recycling role and with its RNase L inhibitor role. Supporting Evidence: Reactome:R-HSA-8985201 ATP-binding cassette sub-family E member 1 (ABCE1, aka RNase L inhibitor, RLI) is a member of the ATP-binding cassette transporters which express in the cytoplasm and the nuclear membrane. |
| GO:0005739 mitochondrion | IDA PMID:11585831 The 2-5A/RNase L/RNase L inhibitor (RLI) [correction of (RNI... | KEEP AS NON CORE | Summary: A mitochondrial fraction of ABCE1/RLI was reported in the context of interferon-induced regulation of mitochondrial mRNA stability. Reason: The localization is supported, but current evidence indicates ABCE1's core conserved function is cytosolic ribosome recycling rather than a primary mitochondrial matrix function. Supporting Evidence: PMID:11585831 We found that a fraction of cellular RNase L and RLI is localized in the mitochondria. |
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Download this section (compressed HTML)Q: Does ABCE1's experimentally observed GTPase, CTPase and UTPase activity have physiological roles, or is ATP hydrolysis the only relevant nucleotide cycle in cells?
Q: What is the precise mitochondrial compartment and context for ABCE1 association: soluble mitochondrial fraction, matrix, mitochondrial outer membrane-associated translation quality control, or stress-induced relocalization?
Q: How does the N-terminal 4Fe-4S cluster domain mechanistically couple the ABC ATPase cycle to ribosome splitting?
Experiment: Reconstitute human ABCE1 with mammalian eRF1/eRF3 and PELO/HBS1L ribosomal complexes using nucleotide-specific ATP, GTP, CTP and UTP conditions, then compare subunit splitting and factor-release kinetics.
Hypothesis: ATP hydrolysis is the physiologically relevant nucleotide cycle for ABCE1 ribosome splitting, while GTP and CTP hydrolysis reflect broader in vitro substrate tolerance.
Experiment: Use endogenous tagging plus protease protection, carbonate extraction and purified mitochondrial subfractionation before and after mitochondrial damage to distinguish matrix localization from outer membrane-associated ribosome quality-control recruitment.
Hypothesis: Most mitochondrial ABCE1 signal reflects stress- or translation-associated recruitment to mitochondrial outer membrane mRNP/ribosome complexes rather than stable matrix localization.
Experiment: Compare wild-type ABCE1 with Fe-S cluster-disrupting mutants in human ribosome splitting assays and cryo-EM of termination and PELO/HBS1L rescue complexes.
Hypothesis: The 4Fe-4S domain is required to position or allosterically activate ABCE1 for productive ATP-driven ribosome disassembly.
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