ASL catalyzes the reversible cleavage of L-argininosuccinate to L-arginine + fumarate (EC 4.3.2.1;
RHEA:24020). It is the third/final step of the L-arginine biosynthesis branch and the second-to-last
step of the urea cycle (cytosolic).
ASL has a well-documented structural role in assembling a NOS-containing multiprotein complex that
channels arginine to nitric oxide synthase; this is independent of catalytic activity.
Argininosuccinic aciduria (ASA / ASLD; MIM 207900; MONDO:0008815), autosomal recessive, second most
common urea cycle disorder (~1 in 70,000; dismech kb/disorders/Argininosuccinic_Aciduria.yaml). Beyond
hyperammonemia, chronic ammonia-independent complications (neurocognitive, hepatic fibrosis, systemic
hypertension) are attributed in part to cell-autonomous NO deficiency (PMID:22081021).
Cytosolic enzyme (GO:0005829). UniProt DR: cytosol IBA (GO_Central), cytoplasm TAS (ProtInc,
PMID:282632). Also detected in urinary exosomes by large-scale proteomics PMID:19056867 — a
mass-spec location catalog finding, not a curated site of action.
The preceding notes are a historical record; the reassessment below supersedes conflicting scope or evidence claims.
This is a working assessment, not a completed review. The existing human P04424 review has 31 authored rows, including a proposed scaffold annotation, and three alternative products. A separate deterministic seed restores 17 WITH/FROM lists and two distinct HuRI interaction assertions. All 31 prior row objects and decisions remain preserved in that preparatory file; the canonical review is unchanged. The existing falcon report is reused as background. Its selected functional sections were inspected; its mechanistic and evolutionary claims are not accepted without their primary evidence.
The complete abstract bodies of all 13 cited PMID caches were read. Full-text availability is distinct from complete reading of a paper. In particular, the cached structure papers 11747432 and 11747433 are abstract-only, while 22081021 contains body text. No source cache was edited. The ordinary PMID caching command succeeded using existing records. One normal fetch attempt for each missing Reactome record failed on DNS resolution and produced no file; those two normal records still need recovery.
ASL catalyzes argininosuccinate cleavage into arginine and fumarate. The human complementation experiments distinguish active-site restoration in mixed Q286R/D87G tetramers from stabilization involving M360T or A398D. Human COS-cell assays in 9045711 and 2263616 independently support the enzyme assignment. The abstract of 11747432 describes the Q286R structure and comparison with duck crystallins, but does not give the quoted 0.12 mM kinetic value. That value is recorded in UniProt and should not be represented as independently read from this paper's body. The existing two catalytic core entries can be combined into one function connected to both urea-cycle and arginine-biosynthesis processes. PMID:11747432(https://pubmed.ncbi.nlm.nih.gov/11747432/), PMID:11747433(https://pubmed.ncbi.nlm.nih.gov/11747433/), PMID:9045711(https://pubmed.ncbi.nlm.nih.gov/9045711/), PMID:2263616(https://pubmed.ncbi.nlm.nih.gov/2263616/).
The selected original Results section on NOS-complex maintenance in 22081021 was read in the normal cache. The species and experimental boundaries matter: mouse lung and brain immunoprecipitations address Nos3- and Nos1-containing assemblies, respectively. Human R236W ASL was tested in COS7 assembly assays. Human R113Q ASL was expressed in patient fibroblasts and restored arginine-stimulated nitrite production. These are distinct experiments, not two mutant proteins both tested for every outcome in human tissues. The paper supports a structural contribution beyond arginine-generating catalysis. It does not establish direct pairwise binding to every component or simultaneous inclusion of all three NOS paralogs in one universal complex. The selected Results and complete abstract were read, not all supplementary tables, figure pixels or methods. PMID:22081021(https://pubmed.ncbi.nlm.nih.gov/22081021/).
The current GO definition of protein complex scaffold activity requires a structural component that holds a protein complex together. Its parent is structural molecule activity. The preexisting proposed MF can be assessed against the actual assembly/rescue experiments; this is not an inference merely from knockout necessity or from another protein having an annotation. If retained as a core scaffold function, the human NO-regulation annotation should have a consistent core decision rather than calling the same function both core and non-core. No new process term is being proposed. The local GO-CAM index has no exact UniProtKB:P04424 entry. GO:0140378.
The current official Reactome pages were independently read. R-HSA-70573 describes the reversible reaction with a cytosolic human ASL tetramer catalyst. R-HSA-9956524 models loss of function of cytosolic ASL variant tetramers and links the normal reaction. These pages support the source identities and cytosolic context; normal cache recovery is still separate. No inference that all variant proteins preserve catalytic activity follows from the reaction's catalyst label. Reactome:R-HSA-70573, Reactome:R-HSA-9956524.
The generic interaction rows need source-specific assessment. The restored supporting entities distinguish NTAQ1, MCMBP isoform 2 and TRIM3; a partner's isoform suffix is not an ASL isoform assignment. No target-specific high-throughput table was read at this stage. The homotetramer is independently supported, so self-association can be corroborated without claiming to have rechecked each screen. General binding should not be called false merely because it is nonspecific. The urinary-exosome target entry was not inspected; the existing claims of nonfunctional extracellular localization and bystander detection exceed the accessible evidence. Source-specific uncertainty should be retained without asserting contamination. PMID:19056867(https://pubmed.ncbi.nlm.nih.gov/19056867/).
PAINT source nodes and descendant evidence must remain intact. Agreement with human experimental evidence supports the transferred functions but does not reconstruct the ancestral tree, and a human self-donor is not circular. The mouse NO-regulation transfer must retain its original donor chain even when the independent human study corroborates the function.
The working revision consolidates the two catalytic cores, retains the preexisting scaffold proposal with primary Results support, and makes nitric-oxide action decisions consistent with that second core. All 33 source objects and three alternative products are preserved. Publication awaits independent consultation and normal Reactome cache recovery.
Independent annotation consultation prompted two precision corrections: broad arginine metabolism is MODIFY to arginine biosynthesis, and the bioautography attachment was removed from the cytosol row because it does not demonstrate localization. The original all-33 prospective map records the earlier decisions.
The original Results label the fibroblast rescue mutant R113Q, while the indexed official Fig. 6c caption labels it R113W. The residue identity is reported here as stated in the Results; the within-paper discrepancy is unresolved and does not change the demonstrated catalytic-site-mutant rescue. Root and the independent reviewer read the indexed official PMC Fig. 6 caption; no figure pixels or supplementary Methods were inspected. The caption also identifies NOS3 and ASS antibodies in the COS7 experiment. PMID:22081021, Fig. 6.
Both missing normal Reactome records are now recovered and were read in full. The earlier pending statements describe preparation and are resolved. The normal reaction summary explicitly places the ASL homotetramer in the cytosol. The variant summary distinguishes candidate from characterized mutant members; its compartment comes from the independently inspected official event/catalyst pages. The source files remain unmodified. The independent all-33 annotation consultation passed, including preservation of every source assertion and all three alternative products. The prospective consultation found 23 ACCEPT, 2 MODIFY, 7 UNDECIDED and one retained preexisting NEW scaffold molecular function; subsequent direct exosome evidence resolves one UNDECIDED as KEEP_AS_NON_CORE. No additional NEW assertion was introduced.
The study-authored NHLBI Urinary Exosome Protein Database lists ASL NP_001020117 with one peptide and reference 2, explicitly linked to PMID:19056867. The root read this exact row and the reference mapping. The final exosome action is KEEP_AS_NON_CORE on direct target evidence. No claim of exosomal catalysis, contamination, peptide uniqueness or modern isoform assignment follows. Final totals are 23 ACCEPT, 2 MODIFY, 6 UNDECIDED, 1 KEEP_AS_NON_CORE and the retained NEW scaffold function.
The exact published head 3661229d710129418f193d0ec73818214daa5b47 received a substantive review on 2026-09-28 at 22:10 UTC. The fresh complete review/comment and CI response was read; required tests and the review job completed successfully. The earlier quota observation is historical and does not describe this current review.
The scaffold decision remains supported by the original study. The targeted cached Results explicitly compare NOS-complex co-immunoprecipitation with and without ASL in the human-ASL COS7 experiment and report reduced assembly in hypomorphic mouse lung/brain despite increased individual protein abundance. These directly address structural complex maintenance. Catalytically inactive human R236W ASL preserving assembly addresses catalysis independence, and the patient-fibroblast mutant rescue addresses NO output. Each is a different part of the argument; rescue alone is not used as evidence that ASL holds a complex together. Exact cached absence/assembly passages now accompany the existing retained NEW scaffold row, the NO-process rows and the second core. The current official GO:0140378 definition and structural-molecule parent were read independently.
The new description states ASL's biological roles downstream of ASS1, its tissue-dependent NOS assembly context including SLC7A1/CAT-1 and HSP90, and systemic manifestations that can persist despite ammonia control. These statements follow the actual primary Introduction/Results/Discussion and shipped UniProt FUNCTION/SUBUNIT blocks; the latter's tissue-complex SUBUNIT assertion is explicitly by similarity. No universal human NOS1/NOS2/NOS3 complex, direct binding to every partner, or sole NO explanation for disease is asserted. Full Methods, supplementary tables and figure pixels remain unread in this follow-up.
The R113Q/R113W discrepancy remains documented in the reference assessment and earlier notes; the duplicate long caveats in two row reasons are replaced by a cross-reference. Reactome's explicit R113Q listing corroborates the Results label but is not an erratum and does not establish which panel label was intended.
The broad arginine-metabolism refinement retains the original PMID:9045711 IDA source. Its activity quote remains, with a separate exact PMID:11747432 biosynthesis passage added as process corroboration. Homotetramerization and composite catalytic sites are stated within the existing lyase core and supported by the complete cached human complementation abstract. No separate core is required merely to duplicate every ACCEPT annotation identifier.
The six generic-binding actions remain UNDECIDED under the explicit user inaccessible-evidence rule. Their source-specific NTAQ1, MCMBP isoform 2 and TRIM3 records have not been inspected. The shipped UniProt aggregation is corroboration of partner association, not a newly read original assay. Genericity alone does not establish incorrectness under the user's REMOVE definition; the conflicting repository policy remains an unresolved instruction question. No consent is inferred and no automatic REMOVE is made. Partner isoform suffixes continue to describe the partner, not an ASL isoform.
All 33 annotation source objects (32 original assertions plus the retained scaffold proposal), all actions, three products, core term identities and process/location edges remain unchanged. No new annotation or process, source fetch, cache modification, history rewrite or remote response is included in this prospective draft.
The review of PR #3385 at 500bfca53 correctly distinguishes informational exclusion from a claim that an interaction is false. The default binding policy can exclude an uninformative term even when an association is real. The earlier discussion should not be read as saying that this default requires biological falsity.
The six unresolved assertions cite four distinct papers: PMID:25416956, PMID:26871637, PMID:31515488 and PMID:32296183. Their partners are identified as NTAQ1, MCMBP isoform 2 and TRIM3. General screening methods and full_text_available: true establish neither inspection of each target-specific experiment nor adjudication of its constructs and controls. Conversely, an uninspected supplementary table does not show that the paper omitted or misattributed the interaction. The known partner identifiers, the general assay class and the remaining target-level evidence gap are different facts.
For this task, the explicit evidence-access instruction preserves UNDECIDED when the relevant experiment cannot be adjudicated, and generic binding is not removed solely for informativeness. These six decisions follow those scoped instructions. They do not establish a blanket rule to retain every interaction, claim compliance with the default informational-exclusion policy, or revise a global skill. The MCMBP isoform suffix continues to identify the partner rather than an ASL product.
This addendum adds no source reading, assay verification or quotation. All 32 original assertions, the existing single scaffold proposal, three products and two core functions remain unchanged. The NOS-complex assembly evidence is not transferred to unrelated screen partners. The review's COMPLETE status records completion of its curation decisions; it does not turn the six UNDECIDED actions into verified experimental claims.