GO_REF:0000024

GO reference used by source annotation pipeline

Source annotation pipeline provenance for Gsta1 annotations including glutathione derivative biosynthetic process; prostaglandin metabolic process; steroid Delta-isomerase activity.

"GO_REF entry used only to trace the source annotation method; biological support was assessed against UniProt and cached literature where available."

GO_REF:0000033

GO reference used by source annotation pipeline

Source annotation pipeline provenance for Gsta1 annotations including cytosol; glutathione metabolic process; glutathione transferase activity; xenobiotic metabolic process.

"GO_REF entry used only to trace the source annotation method; biological support was assessed against UniProt and cached literature where available."

GO_REF:0000044

GO reference used by source annotation pipeline

Source annotation pipeline provenance for Gsta1 annotations including cytoplasm.

"GO_REF entry used only to trace the source annotation method; biological support was assessed against UniProt and cached literature where available."

GO_REF:0000108

GO reference used by source annotation pipeline

Source annotation pipeline provenance for Gsta1 annotations including cellular oxidant detoxification.

"GO_REF entry used only to trace the source annotation method; biological support was assessed against UniProt and cached literature where available."

GO_REF:0000116

GO reference used by source annotation pipeline

Source annotation pipeline provenance for Gsta1 annotations including phospholipid-hydroperoxide glutathione peroxidase activity; steroid Delta-isomerase activity.

"GO_REF entry used only to trace the source annotation method; biological support was assessed against UniProt and cached literature where available."

GO_REF:0000120

GO reference used by source annotation pipeline

Source annotation pipeline provenance for Gsta1 annotations including glutathione transferase activity.

"GO_REF entry used only to trace the source annotation method; biological support was assessed against UniProt and cached literature where available."

GO_REF:0000121

GO reference used by source annotation pipeline

Source annotation pipeline provenance for Gsta1 annotations including cytosol; epithelial cell differentiation; glutathione transferase activity; mitochondrion; response to bacterium; and 1 other terms.

"GO_REF entry used only to trace the source annotation method; biological support was assessed against UniProt and cached literature where available."

PMID:10395737

The role of human glutathione S-transferases hGSTA1-1 and hGSTA2-2 in protection against oxidative stress.

PMID:10751412

The catalytic Tyr-9 of glutathione S-transferase A1-1 controls the dynamics of the C terminus

For Gsta1, this publication provides evidence/provenance for direct annotations to glutathione transferase activity and contextual annotations to glutathione binding.

"The glutathione S-transferase enzymes (GSTs) have a tyrosine or serine residue at their active site that hydrogen bonds to and stabilizes the thiolate anion of glutathione, GS(-)."

PMID:11119643

Localization of the C-terminus of rat glutathione S-transferase A1-1: crystal structure of mutants W21F and W21F/F220Y

For Gsta1, this publication supports direct annotations to glutathione transferase activity.

"Twelve C-terminal residues of human glutathione S-transferase A1-1 form a helix in the presence of glutathione-conjugate, or substrate alone, and partly cover the active site."

PMID:15152091

Heterodimers of wild-type and subunit interface mutant enzymes of glutathione S-transferase A1-1: interactive or independent active sites?

For Gsta1, this publication provides evidence/provenance for direct annotations to glutathione transferase activity and contextual annotations to glutathione binding; protein homodimerization activity.

"Heterodimers of rat glutathione S-transferase A1-1 were formed using one wild-type subunit and one subunit with a mutation at the interface to evaluate whether the subunits are interactive or independent."

PMID:17112229

Site-specific arylation of rat glutathione s-transferase A1 and A2 by bromobenzene metabolites in vivo

For Gsta1, this publication provides evidence/provenance for direct annotations to glutathione transferase activity; xenobiotic catabolic process and contextual annotations to cytosol; glutathione binding.

"The hepatotoxicity of bromobenzene (BB) derives from its reactive metabolites (epoxides and quinones), which arylate cellular proteins."

PMID:17197701

Electrostatic association of glutathione transferase to the nuclear membrane. Evidence of an enzyme defense barrier at the nuclear envelope

For Gsta1, this publication was reviewed as context for dinitrosyl-iron complex binding.

"The possible nuclear compartmentalization of glutathione S-transferase (GST) isoenzymes has been the subject of contradictory reports."

file:rat/Gsta1/Gsta1-deep-research-falcon.md

Falcon (Edison Scientific) deep research report on rat Gsta1 (P00502)

Falcon verified identity (UniProt P00502 = rat Gsta1, cytosolic alpha-class GST / GST A1-1 / ligandin) and corroborates the canonical phase II glutathione-conjugation function.

"**Glutathione S-transferases (GSTs)** are enzymes best known for catalyzing **phase II detoxification** reactions by promoting the **conjugation of reduced glutathione (GSH)** to a wide range of **electrophilic** endogenous and exogenous compounds, thereby increasing their solubility and facilitating elimination."
Falcon describes the cytosolic GST fold (homodimer, thioredoxin-like N-terminal domain, GSH G-site plus hydrophobic substrate site), corroborating the homodimerization and glutathione-binding annotations.

"Mammalian cytosolic GSTs are typically **homodimers** and have an N-terminal domain with a thioredoxin-like fold; they contain a **G-site** that binds GSH and a hydrophobic substrate-binding site."
Falcon corroborates alpha-class selenium-independent glutathione peroxidase (GPx)-like activity toward lipid and sterol hydroperoxides and conjugation of lipid-derived electrophiles such as 4-HNE, supporting the secondary peroxidase / oxidant-detoxification annotations.

"In mammalian systems, **A-class (alpha) GSTs** are noted for (i) high activity in detoxification pathways and (ii) **selenium-independent glutathione peroxidase (GPx)-like activity**, including reduction of lipid and sterol hydroperoxides in membranes. Anionic A-class enzymes are described as efficient catalysts for conjugation of lipid-derived electrophiles such as **4-hydroxynonenal (4-HNE)**."
Falcon supports cytosolic localization as the primary site of Gsta1 function.

"The evidence base supports the view that GSTs are primarily **cytosolic enzymes**, consistent with cytosolic GST fold proteins and classic phase II metabolism."
Falcon notes isomerase and non-enzymatic ligandin (ligand-binding) functions as recognized alpha-class GST activities, consistent with the steroid Delta-isomerase and binding annotations.

"- **Ligandin/binding functions** (non-enzymatic ligand binding; historically associated with alpha-class GSTs) (stoian2025modulationofglutathionestransferase pages 1-2)"
Falcon explicitly cautions that the detailed small-molecule substrate list it reports is from a human GSTA1 table and must not be transferred to rat P00502 without direct rat evidence, since substrate specificity varies among the near-identical alpha paralogs (Gsta1 vs Gsta2/3/4). This caveat is the basis for keeping broad substrate-level annotations cautious and not asserting paralog-specific substrates.

"**Species transfer requires caution.** While mammalian alpha-class GSTs are functionally similar, substrate specificity can vary between paralogs (Gsta1 vs Gsta2/3/4) and species; thus, rat-specific experiments should be sought for precise annotation of P00502."