Protein trafficking
What proteins build the caveolar coat?
Open access · cc by · source: Europe PMC
Caveolins and cavins purify as a caveolar coat complex with Cavin 1 as a core trimeric component.
Study at a glance
- Design
- Animal / in-vitro — Biochemical purification and ultrastructure of caveolar coat proteins
- N
- Structural/biochemical coat stoichiometry study — no single sample N
- Population
- Caveolar coat complexes (caveolins/cavins)
- Outcome
- Molecular composition and ultrastructure of the caveolar coat
Structured fields used in claim comparison tables when every cited study has a complete layer.
Key findings
Caveolins and cavins form one complex excluding EHD2/pacsin 2; Cavin 1 is a core component with evidence for trimers.
Methodology
Purified caveolar coat proteins and used quantitative composition plus ultrastructure to model coat stoichiometry.
Limitations
Composition model is not a full in vivo dynamics movie of every cell type.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
Three papers in this method list barely use knockout or knockdown. APEX2 proximity labelling mapped 22 outer-mitochondrial and 72 ER-membrane proteins facing the cytosol; scRNA-seq of H1 hESC progenitors found that 1.5% O2 increases CXCR4+ definitive-endoderm-like cells; caveolar-coat work purified caveolin–cavin complexes. Those are maps and culture conditions, not gene deletions.
Evidence for the claim as stated.
Lexicon hits also disagree with the genuine KO/KD set. APEX2 inventories, hESC scRNA-seq under hypoxia, and caveolar stoichiometry do not perturb named genes, so they cannot be cited as knockdown evidence for trafficking proteins they merely list.
Evidence for the claim as stated.
Caveolar-coat purification used quantitative composition to show caveolins and cavins in one complex that excludes EHD2/pacsin 2, with Cavin 1 a core component and evidence for trimers. Western or blot-style detection of coat subunits supports stoichiometry; it is not a live-cell movie of every tissue's caveolae.
Evidence for the claim as stated.
Westerns here answer different biochemical questions. Caveolar work asks which subunits co-purify; N–p50 asks which domain is required for association and HR; USP8 asks whether Smo is ubiquitinated; spike work asks whether glycan occupancy and palmitoylation change S2 mobility and trafficking. A darker band is not a universal 'more protein' story across those designs.
Evidence for the claim as stated.
Several confocal-tagged papers use imaging only as a supporting localisation. APEX2 defined 22 OMM and 72 ERM cytosol-facing proteins by mass spectrometry; caveolar-coat work is biochemical stoichiometry plus ultrastructure (caveolin–cavin complex excluding EHD2/pacsin 2); N and TMV p50 were cytoplasmic in N. benthamiana with TIR-dependent association and HR in two days. Those localisation notes are not confocal trafficking movies.
Evidence for the claim as stated.
APEX2, caveolar ultrastructure, and plant TIR–p50 association are weaker confocal examples: proximity biotinylation, electron-microscopy-scale coat structure, and cytoplasmic HR biochemistry. Citing them as confocal method papers overstates the imaging.
Evidence for the claim as stated.
Purified caveolar coats analysed by quantitative composition showed caveolins and cavins as one complex excluding EHD2/pacsin 2, with Cavin 1 a core component and evidence for trimers. MS-backed stoichiometry is a biochemical model, not a dynamics movie in every cell type.
Evidence for the claim as stated.
Genuine MS designs still disagree about what is being counted. APEX2 inventories membrane-face neighbours in living cells (22 OMM; 72 ERM); caveolar work quantifies a purified coat; Rab5 work maps three ubiquitin lysines; rice work maps histone acylations under stress. A 'proteomics paper' can be spatial, stoichiometric, or epigenetic, and those outputs are not interchangeable.
Evidence for the claim as stated.
Caveolar-coat purification plus ultrastructure showed caveolins and cavins as one complex excluding EHD2/pacsin 2, with Cavin 1 a core component and evidence for trimers. EM here supports a coat model; it is not a full in-vivo dynamics movie of every cell type.
Evidence for the claim as stated.
Only the caveolar paper is clearly an ultrastructure-of-a-coat study. GPCR work compares 142 inactive and 27 active deposited structures; APEX2 is proteomics; salmon work is a 30-day transcriptome of fat-cell differentiation; Bt OMV uptake is live light-microscopy trafficking. Calling all five 'electron microscopy papers' overstates shared methods.
Evidence for the claim as stated.
Resolution targets disagree. Caveolar EM asks about coat stoichiometry (Cavin 1 trimers; exclusion of EHD2/pacsin 2). GPCR contact maps ask about conserved switches across receptors (34 residue pairs). OMV live imaging asks about a 15-minute endocytic route. Those answers cannot substitute for one another.
Evidence for the claim as stated.
Open questions
Tensions this paper is part of
From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.
Lexicon hits also disagree with the genuine KO/KD set. APEX2 inventories, hESC scRNA-seq under hypoxia, and caveolar stoichiometry do not perturb named genes, so they cannot be cited as knockdown evidence for trafficking proteins they merely list.
Westerns here answer different biochemical questions. Caveolar work asks which subunits co-purify; N–p50 asks which domain is required for association and HR; USP8 asks whether Smo is ubiquitinated; spike work asks whether glycan occupancy and palmitoylation change S2 mobility and trafficking. A darker band is not a universal 'more protein' story across those designs.
- Supports · Plant TIR domain binds viral elicitor
- Supports · How does USP8 turn on Smoothened?
- Supports · Spike glycosylation and palmitoylation trafficking
APEX2, caveolar ultrastructure, and plant TIR–p50 association are weaker confocal examples: proximity biotinylation, electron-microscopy-scale coat structure, and cytoplasmic HR biochemistry. Citing them as confocal method papers overstates the imaging.
- Supports · Mapping the faces of mitochondria and ER
- Supports · Plant TIR domain binds viral elicitor
Genuine MS designs still disagree about what is being counted. APEX2 inventories membrane-face neighbours in living cells (22 OMM; 72 ERM); caveolar work quantifies a purified coat; Rab5 work maps three ubiquitin lysines; rice work maps histone acylations under stress. A 'proteomics paper' can be spatial, stoichiometric, or epigenetic, and those outputs are not interchangeable.
- Supports · Mapping the faces of mitochondria and ER
- Supports · How does monoubiquitin turn down Rab5?
- Supports · Histone acylations respond to plant stress
Only the caveolar paper is clearly an ultrastructure-of-a-coat study. GPCR work compares 142 inactive and 27 active deposited structures; APEX2 is proteomics; salmon work is a 30-day transcriptome of fat-cell differentiation; Bt OMV uptake is live light-microscopy trafficking. Calling all five 'electron microscopy papers' overstates shared methods.
- Supports · Shared class A GPCR activation path
- Supports · Mapping the faces of mitochondria and ER
- Supports · Salmon fat-cell differentiation transcriptome
- Supports · How do gut-bacteria vesicles enter host cells?
Resolution targets disagree. Caveolar EM asks about coat stoichiometry (Cavin 1 trimers; exclusion of EHD2/pacsin 2). GPCR contact maps ask about conserved switches across receptors (34 residue pairs). OMV live imaging asks about a 15-minute endocytic route. Those answers cannot substitute for one another.
- Supports · Shared class A GPCR activation path
- Supports · How do gut-bacteria vesicles enter host cells?
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Same topic cluster — not a recommendation engine.