S6K1 (p70 ribosomal protein S6 kinase 1)
S6K1 is directly phosphorylated by mTORC1 at Thr389, the canonical assay marker for mTORC1 activity used throughout this dataset (p-S6K1 Thr389). Active S6K1 promotes ribosomal bio...
Classification
Category: Downstream effector / protein-synthesis kinase
Aliases: p70S6K, RPS6KB1
Relationship to mTOR complexes: Direct mTORC1 substrate; downstream of mTORC1 — see mTORC1 vs mTORC2 for the full complex-level map.
Summary
S6K1 is directly phosphorylated by mTORC1 at Thr389, the canonical assay marker for mTORC1 activity used throughout this dataset (p-S6K1 Thr389). Active S6K1 promotes ribosomal biogenesis and mRNA translation, driving cell growth and protein synthesis.
| Upstream of | none recorded |
| Downstream of | MTORC1 |
- mTORC1 directly phosphorylates S6K1 at Thr389 when mTORC1 is active (nutrient/growth-factor replete state)
- Phosphorylates ribosomal protein S6 and other translation-machinery targets, promoting protein synthesis and cell growth
- p-S6K1 (Thr389) is the specific assay marker this dataset's pathway/assay-reference table designates as 'the' protein-synthesis marker for mTORC1 activity -- referenced on the exercise-mTOR-mechanistic study record and elsewhere.
- S6K1 activation (protein synthesis, anabolism) and ULK1 suppression (reduced autophagy) are the two most-cited, opposing downstream consequences of active mTORC1 in this dataset.
Source tier
Tier 2 · Biological synthesis (author-cluster reviews, not primary trial data) Reference synthesis attributed in the brief to the Saxton & Sabatini; Laplante & Sabatini; and Liu & Sabatini mTOR review literature (author-cluster attribution, tier 2, brief ยง4). Exact article-level PMID/DOI not supplied in the sourcing brief and is not fabricated here.