Concept · biology
Cell signalling
Follow Cell signalling — see important new research and changes in evidence.Change log
What changed
Dated edits to this page's evidence: studies added or removed from a claim, claims added or withdrawn, and new explanations tagged here. Rewordings are not listed.
- Concept page published
Cell signalling is how cells detect cues and transmit information through receptors and intracellular pathways to change behaviour.
Signalling pathways explain how cells decide; students meet them in every physiology and development course.
Evidence
What the evidence shows
Drawn from 7 studies in this library. Each finding starts with a plain-language takeaway, then the denser detail. Supports means evidence for a finding; Challenges means evidence against a stated position; Qualifies marks scope with a short note on each study’s contribution. Challenged positions are labeled — they are not findings.
Multiple empirical papers in this library examine cell signalling with mechanistic biological findings.
- Shared class A GPCR activation path
- How does USP8 turn on Smoothened?
- LOX1 oxylipins close stomata in defense
Study Role Design N Population Outcome Shared class A GPCR activation path Supports Computational / modellingResidue–residue contact score comparison across inactive and active Class A GPCR structures N=169 · 142 inactive and 27 active structures compared Class A GPCR crystal/cryo-EM structures Conserved 34-residue-pair activation contact pathway How does USP8 turn on Smoothened? Supports Animal / in-vitroRNAi screen of Drosophila DUBs in wings and S2 cells focused on USP8–Smo regulation Drosophila genetics and S2 cell assays — no single sample N Drosophila tissues and S2 cells USP8 prevention of Smoothened ubiquitination promoting Hedgehog signaling LOX1 oxylipins close stomata in defense Supports Animal / in-vitroArabidopsis LOX1 mutants tested for stomatal immunity and Pst colonization Plant mutant phenotyping; no single primary analytic N in stored text Arabidopsis thaliana (lox1 mutants vs wild type/complemented lines) Stomatal closure and Pst leaf colonization controlled by LOX1/oxylipins A 34-residue-pair pathway across layers; comparisons used 142 inactive and 27 active structures (p<0.001).
USP8 prevents Smo ubiquitination and enhances signaling; Hh promotes Smo–USP8 interaction; USP8 is required for Hh-induced surface accumulation and keeps Smo out of Rab5 early endosomes.
LOX1 is guard-cell expressed; lox1 mutants show >10-fold more Pst growth and impaired flg22/Pst-induced stomatal closure.
103 genes on 32 genomes (87 functional, 16 pseudogenes); vertebrates have the largest counts; Archaea nearly lack HSP90.
Open questions
Tensions and limits
Some items are genuine disagreements on the same question. Others mark different assays, populations, or outcomes — limits on how far one study travels — not a forced fight between papers.
Systems and scales differ across cell signalling studies (species, tissues, methods), so mechanisms should not be over-generalised.
- Shared class A GPCR activation path
- How does USP8 turn on Smoothened?
- LOX1 oxylipins close stomata in defense
Study Role Design N Population Outcome Shared class A GPCR activation path Supports Computational / modellingResidue–residue contact score comparison across inactive and active Class A GPCR structures N=169 · 142 inactive and 27 active structures compared Class A GPCR crystal/cryo-EM structures Conserved 34-residue-pair activation contact pathway How does USP8 turn on Smoothened? Supports Animal / in-vitroRNAi screen of Drosophila DUBs in wings and S2 cells focused on USP8–Smo regulation Drosophila genetics and S2 cell assays — no single sample N Drosophila tissues and S2 cells USP8 prevention of Smoothened ubiquitination promoting Hedgehog signaling LOX1 oxylipins close stomata in defense Supports Animal / in-vitroArabidopsis LOX1 mutants tested for stomatal immunity and Pst colonization Plant mutant phenotyping; no single primary analytic N in stored text Arabidopsis thaliana (lox1 mutants vs wild type/complemented lines) Stomatal closure and Pst leaf colonization controlled by LOX1/oxylipins
Common misconceptions
Cell signalling findings from one model organism always transfer to humans.
Model systems teach mechanism; transfer to other species is a separate empirical claim.
Exam-style questions
Short-answer questions that ask you to explain or compare, not recall.
What is Cell signalling?
Cell signalling is how cells detect cues and transmit information through receptors and intracellular pathways to change behaviour.
Why does Cell signalling matter for biology undergraduates?
Signalling pathways explain how cells decide; students meet them in every physiology and development course.
The studies
7 studies in this library bear on Cell signalling, ordered by citations.
- When does Wnt5a turn β-catenin signaling on or off?
Purified Wnt5a can activate or inhibit β-catenin–TCF signaling depending on which Frizzled/receptor context is present.
- Shared class A GPCR activation path
Class A GPCRs share a conserved residue-contact rearrangement pathway from ligand pocket to G-protein site.
- CPK3/6 mediate ABA guard-cell signaling
Calcium-dependent kinases CPK3 and CPK6 act in ABA control of guard-cell anion/Ca²⁺ channels and stomatal closure.
- How specific are bacterial two-component pathways?
Caulobacter histidine kinases prefer their cognate response regulators in vitro; phosphotransfer profiling reveals conserved pathways controlling growth.
- HSP90 family across kingdoms
Comparative genomics maps 103 HSP90-family genes across 32 genomes and deep phylogenetic diversity.
- LOX1 oxylipins close stomata in defense
Guard-cell LOX1 drives ABA-independent stomatal closure that limits Pseudomonas colonization.
- How does USP8 turn on Smoothened?
USP8 deubiquitinates Smoothened, promoting Hh-dependent cell-surface accumulation and signaling while limiting early-endosome localization.
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