Concept
Cell signalling
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 claim links to the studies behind it.
Multiple empirical papers in this library examine cell signalling with mechanistic biological findings.
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
Where studies disagree
Open questions, not settled findings — worth knowing before you cite any one of these.
Systems and scales differ across cell signalling studies (species, tissues, methods), so mechanisms should not be over-generalised.
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
- 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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