# ABCE1 notes

ABCE1 (UniProt P61221; RLI/RNase L inhibitor) is best curated as a conserved cytosolic Fe-S ABC ATPase whose core role is ribosome recycling. The primary human biochemical evidence is PMID:20122402, which reports that ABCE1 dissociates eukaryotic post-termination complexes into free 60S subunits and mRNA/tRNA-bound 40S subunits, and that NTP hydrolysis is required for this recycling activity [PMID:20122402 "ABCE1 dissociates post-TCs into free 60S subunits and mRNA- and tRNA-bound 40S subunits"; PMID:20122402 "NTP hydrolysis by ABCE1 is stimulated by post-TCs and is required for its recycling activity"].

ABCE1 also participates in stalled-ribosome rescue with PELO/Pelota and HBS1L/Hbs1. PMID:21448132 supports the GO rescue/disassembly annotations because mammalian Pelota/Hbs1-induced dissociation of stalled elongation complexes required ABCE1; Pelota and ABCE1 were essential, while Hbs1 was stimulatory [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"].

The N-terminal Fe-S region is better represented as 4 iron, 4 sulfur cluster binding than generic iron ion binding. UniProt lists the 4Fe-4S domains and a GO cross-reference to GO:0051539, and the falcon research summary describes ABCE1 as an Fe-S ABC ATPase with an N-terminal 4Fe-4S domain required for ribosome recycling [file:human/ABCE1/ABCE1-deep-research-falcon.md "ABCE1 is unusual among ABC proteins in possessing an N-terminal **Fe–S domain**"].

RNase L inhibition is real but non-core relative to ribosome recycling. The original RLI paper supports endoribonuclease inhibitor activity and negative regulation of RNase L, while generic protein binding should be removed in favor of those specific annotations [PMID:7539425 "RLI cDNA codes for a 68-kDa polypeptide"; PMID:7539425 "Its expression in reticulocyte extracts antagonizes the 2-5A binding ability and the nuclease activity of endogenous RNase L"].

Mitochondrial association is supported but should be curated carefully. PMID:11585831 reports a mitochondrial fraction of RNase L and RLI/ABCE1 in interferon-treated H9 cells, but this does not establish a stable mitochondrial matrix localization. PMID:29861391 adds a more specific stress context, where mitochondrial damage recruits Pelo, ABCE1 and NOT4 to mitochondrial outer membrane-associated mRNP quality-control complexes [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"].

Generic protein binding annotations were removed because they either represent viral interactions (HIV-1 Gag, Chandipura virus matrix protein), high-throughput interactome records, or RNase L association that is more specifically captured by endoribonuclease inhibitor activity.

Proteostasis PN context: the PN projection places ABCE1 under `Translation|Cytosolic translation|Translation termination|Ribosome splitting`, which is already captured by `GO:0006415 translational termination`, and under `Translation|Cytosolic translation|Ribosome-associated QC|Ribosomal rescue`, which is already captured by `GO:0072344 rescue of stalled cytosolic ribosome` [projects/PROTEOSTASIS/reports/pn_projection/pn_projected_gene_go_summary.tsv]. The broader PN RQC-group projection to `GO:0006515 protein quality control for misfolded or incompletely synthesized proteins` is biologically defensible for ABCE1 because direct stalled-ribosome rescue evidence shows ABCE1 is required with Pelota/Hbs1 for dissociation of stalled elongation complexes [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"]. Curate this broad term as a supported parent/context annotation, while keeping `GO:0072344` and `GO:0032790` as the more precise core process terms.