Component
O-phosphoseryl-tRNA Sec
Independent entity for contextual scientific-audit claims; no universal nutritional effect implied.
3 recorded relationships. Experimental role, claim status and evidence remain attached to each record.
How nutrients influence it
Every nutrient with a recorded effect on this component, credited to the nutrient that acted rather than the chapter that recorded it. Open a nutrient to see the findings and the conditions they were measured under.
Other things that act on it
Enzymes, hormones, genes, and other components with a recorded effect. These are not nutrients, so they do not count toward the arrows above. Each finding names the chapter that recorded it.
How nutrients reach it in more than one step
Chains of two or more recorded steps that end here, grouped by the nutrient they start from. Each step is a separate finding, so a chain is a route a mechanism could take, not proof that it does.
Tracing routes…
What it does
Every recorded relationship this component is part of, grouped by its role. Plain wording comes first; the technical statement follows.
What acts on it
Human SepSecS structural and functional analysis supported correct positioning of tRNA-bound phosphoserine, but not free phosphoserine, for PLP-dependent selenocysteine formation.
Experimental context and source evidence
- evidence_access
- Primary abstract
- experimental_model
- Human SepSecS–tRNA complex structure with enzyme assays.
- limitations
- Free phosphoserine and a phosphoserine residue on this specialized tRNA are not interchangeable substrates.
- nutrient_topic
- L-Serine collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · L-Serine
- plain_language
- The carrier and the cofactor are part of the reaction, not optional packaging.
- primary_references
- The human SepSecS-tRNASec complex reveals the mechanism of selenocysteine formation. · 2009 · https://pubmed.ncbi.nlm.nih.gov/19608919/ · DOI 10.1126/science.1173755
L-Serine: synthesis, one-carbon metabolism, lipids and cross-nutrient mechanisms (2026-09-19) · lines 390–396
AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Human SepSecS–tRNA complex structure with enzyme assays. · source_derived_draft · unverified_draft
## l-serine-sepsecs-substrate The carrier and the cofactor are part of the reaction, not optional packaging. Human SepSecS structural and functional analysis supported correct positioning of tRNA-bound phosphoserine, but not free phosphoserine, for PLP-dependent selenocysteine formation. Model: Human SepSecS–tRNA complex structure with enzyme assays. Limitations: Free phosphoserine and a phosphoserine residue on this specialized tRNA are not interchangeable substrates. Evidence access: Primary abstract The human SepSecS-tRNASec complex reveals the mechanism of selenocysteine formation. · 2009 · https://pubmed.ncbi.nlm.nih.gov/19608919/ · DOI 10.1126/science.1173755
Complete structured claim and evidence
Where it participates (unsigned role)
Human PSTK phosphorylates serine attached to tRNA Sec as part of the specialized selenocysteine synthesis pathway.
Experimental context and source evidence
- evidence_access
- Primary abstract
- experimental_model
- Purified human PSTK with tRNA substrates; comparison with KTI12.
- limitations
- This is tRNA-bound serine chemistry, not direct conversion of free serine into free selenocysteine.
- nutrient_topic
- L-Serine collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · L-Serine
- plain_language
- A serine molecule already loaded onto a tRNA is processed into a selenium-containing amino-acid precursor.
- primary_references
- Same but different - Molecular comparison of human KTI12 and PSTK. · 2021 · https://pubmed.ncbi.nlm.nih.gov/33417976/ · DOI 10.1016/j.bbamcr.2020.118945
L-Serine: synthesis, one-carbon metabolism, lipids and cross-nutrient mechanisms (2026-09-19) · lines 382–388
AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Purified human PSTK with tRNA substrates; comparison with KTI12. · source_derived_draft · unverified_draft
## l-serine-pstk-serine A serine molecule already loaded onto a tRNA is processed into a selenium-containing amino-acid precursor. Human PSTK phosphorylates serine attached to tRNA Sec as part of the specialized selenocysteine synthesis pathway. Model: Purified human PSTK with tRNA substrates; comparison with KTI12. Limitations: This is tRNA-bound serine chemistry, not direct conversion of free serine into free selenocysteine. Evidence access: Primary abstract Same but different - Molecular comparison of human KTI12 and PSTK. · 2021 · https://pubmed.ncbi.nlm.nih.gov/33417976/ · DOI 10.1016/j.bbamcr.2020.118945
Complete structured claim and evidencePLP-dependent SEPSECS converts phosphoseryl-tRNA Sec to Sec-tRNA through phosphate elimination and selenium donation from selenophosphate, not incorporation of intact selenophosphate.
Experimental context and source evidence
- cell_type
- Purified enzyme/tRNA
- experimental_model
- Human enzyme/tRNA crystallography and biochemical assays
- limitations
- Not a measurement of dietary intake effects.
- organism
- Homo sapiens
Selenium: literature corrections and mechanism additions · lines 1154–1164
Metabolic Ledger literature curation, 17 September 2026; primary papers linked individually · supports · Human enzyme/tRNA crystallography and biochemical assays · secondary_verified · secondary_verified
## sepsecs-chemistry SEPSECS uses selenium from the donor to finish the tRNA-bound amino acid. PLP-dependent SEPSECS converts phosphoseryl-tRNA Sec to Sec-tRNA through phosphate elimination and selenium donation from selenophosphate, not incorporation of intact selenophosphate. Organism: Homo sapiens Cell type: Purified enzyme/tRNA Experimental model: Human enzyme/tRNA crystallography and biochemical assays Limitations: Not a measurement of dietary intake effects. Primary reference: [The human SepSecS–tRNASec complex reveals mechanism of selenocysteine formation](https://pubmed.ncbi.nlm.nih.gov/19608919/)
Complete structured claim and evidence
The events it takes part in
A mechanism often involves more than two components. These are the full events, with every participant and its role.
Situations it appears in
Low-supply and faulty-machinery situations recorded in the chapters where this component plays a part.
In the sources
Preserved passages that mention this component, quoted exactly. Open one to read it in context.
Open hypotheses
Proposed ideas that involve this component. They are labeled as hypotheses and do not change any recorded statement.
This is a research prototype built from draft material. It is not medical advice, and its statements still await verification against the original studies.