FGA supplies the alpha-chain component of fibrinogen, whose two alpha, two beta and two gamma chains form a secreted complex. The native chicken structure describes how the chains interlock at the central domain and extend through coiled coils; its alpha-C and amino-terminal peptide regions remain disordered rather than experimentally absent (PMID:11601975(../../../publications/PMID_11601975.md), printed 12516–12517, purification Methods, central-domain Results and Figures 1–2 captions). The human structural preparation must be described separately because proteolysis during crystallization affects its alpha-C material. Neither structure demonstrates that released fibrinopeptide A is an independent structural member of fibrinogen.
The actual Reactome cleavage event separates intact fibrinogen, the released peptides and fibrin monomer (R-HSA-140840, entities 114618/140841, 140867 and 140586/140583). Fibrin assembly and cross-linking are different steps: the FGA-derived chain provides structure and polymer contacts, while thrombin performs cleavage and Factor XIIIa supplies cross-linking catalysis (R-HSA-140842; R-HSA-140851). Being cleaved alone is insufficient for process participation. Here structural incorporation supplies the positive participation evidence.
FGA also contributes to fibrinolysis through assembly-dependent cofactor activity. Human recombinant alpha-C oligomers bind both tPA and plasminogen and enhance plasmin generation (PMID:21806028(../../../publications/PMID_21806028.md), binding and plasmin-generation Methods/Results and Figures 5–8). Soluble monomers are weaker, internally cross-linked monomers are intermediate, and immobilized-fragment assays must not be treated as equivalent to all these states. The activity supports a two-ligand organizing role; tPA performs the proteolytic activation. The authors explicitly contrast their monomer results with an earlier report (PMID:11170397(../../../publications/PMID_11170397.md)). An untested difference in aggregation state is their proposed explanation, not an experimentally resolved reconciliation. The earlier paper's operative Methods remain inaccessible and that limit is retained.
A later comparison using human plasma material finds lower, but persistent, plasminogen activation after alpha-C truncation (PMID:37082262(../../../publications/PMID_37082262.md), preparation/activation Methods, plasmin-generation Results and Figure 5). Thus alpha-C contributes to a cofactor function without accounting for every fibrin binding site or all activation. The experimental Aalpha221–610 fragment uses the paper's numbering and is not made into a natural product or silently mapped onto current precursor coordinates.
The two curated natural splice precursors, Alpha-E (866 residues) and Alpha (644 residues), remain intact as separate source objects. UniProt's canonical fibrinopeptide A feature is residues 20–35 and its displayed fibrin alpha-chain feature is 36–866. The latter endpoint belongs to the displayed long precursor; it cannot describe the shorter splice form. The six raw processed-product records and their mixed projection groups remain traceable even where the seeding pipeline omitted their product identifiers. A positive gene-level structural or cofactor result does not automatically verify the released peptide's source-specific process or complex annotation.
Reactome models fibrinopeptide A inside a larger TLR4-ligand set (R-HSA-8870678, route 8870680 to 140867). This supplies the modeled extracellular location, without independently demonstrating that the isolated 16-residue peptide is the assayed agonist. Likewise, the FAM20C substrate set models FGA with residues 36–866 in the ER lumen; those coordinates are recorded literally and are not taken as independent proof of fibrinopeptide cleavage inside the ER. The platelet alpha-granule event models FGA-containing cargo in the lumen and after release (R-HSA-481007, routes through 140920 and 140841). Cargo location does not assign exocytosis machinery to FGA.
Protein-level joins in tissue and extracellular-vesicle datasets remain distinct from topology, isoform identity and physiological mechanism. Exact FGA/P02671-containing protein groups can support bounded detection even when they include P02671-2 or additional ambiguous accessions. Unrecovered protein tables are not replaced with a visible FGA transcript heatmap. Source-specific uncertainty remains visible alongside independently supported structural and cofactor biology.
The direct evidence guide and database evidence guide retain the actual article and source locators. The direct journal records the original manual review. The two structural and cofactor core functions do not assign proteolytic catalysis to FGA. All 131 imported source objects and both natural splice records remain unchanged. The two cleavage-product classes describe official features separately; the raw product joins preserve source-specific ambiguity.
All annotation decisions are present: 76 ACCEPT, 33 KEEP_AS_NON_CORE, three MODIFY, six TOO_GENERAL and 13 UNDECIDED. Two YWHAQ associations are refined to 14-3-3 protein binding, and the existing adaptor assertion is refined to enzyme-substrate adaptor activity. No NEW annotation or publication quotation is added. Source-specific uncertainty is preserved where the exact experiment, target identification or processed-product attribution remains unresolved; it is not decided by evidence-code ranking.
The genuine configured research-provider invocation produced no report; its cause was not inspected. Manual notes and the original source guides document the evidence actually assessed.
Supported generic binding remains non-core under the explicit campaign instructions; no new quotations or annotations are added. The BioPlex partner-class refinement retains tagged-construct, detergent-lysate, indirect-association and compartment-compatibility limits. Same-term HDA target joins and mixed free-peptide/mature-chain contexts remain unresolved. Positive heterotypic adhesion is retained as contextual participation within intact fibrinogen by curator deference to PMID:8100742’s abstract, with full-text and chain-contact uncertainty preserved. Structural synthesis now names the extracellular matrix contribution; the cofactor core explicitly includes the already reviewed fibrinolysis process. Natural splice products remain distinct from thrombin-released peptides and experimental alpha-C fragments. The platelet alpha-chain versus gamma-chain recognition question is retained as a question, not a new molecular-function assertion.
The revised totals are 76 ACCEPT, 36 KEEP_AS_NON_CORE, three MODIFY, six TOO_GENERAL and 10 UNDECIDED. Only the three heterotypic-adhesion actions changed; all 131 imported source objects, 90 whole reference objects, both natural splice records and both cleavage-product records remain unchanged. The biological description now states alternative splicing without curation terminology. The original counts above remain as the earlier journal entry.