Concept
Protein trafficking
Protein trafficking is the directed movement of proteins through cellular compartments to their functional destinations.
Where proteins go determines function — trafficking errors underlie many disease mechanisms taught in biology.
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 protein trafficking with mechanistic biological findings.
PDLP1 family proteins target plasmodesmata; PDLP1a has cytoplasmic C-tail and apoplastic DUF26 domains; combined KOs increase GFP movement.
LYQD mutants altered S2 glycosylation mobility; palmitoylation at cysteine clusters I/II was required for efficient S pp/virus production, Golgi/plasma-membrane targeting, and cell fusion.
Rab5 is monoubiquitinated at K116, K140, and K165; K140/K165 modifications downregulate the Rab5 endocytic pathway via disrupted partners and nucleotide conversion, while K116 has little localization effect.
MC4R homodimerizes and undergoes β-arrestin-2–driven endocytosis. Many variants impair trafficking even when cAMP looks normal; gain-of-function alleles link to obesity protection.
Open questions
Where studies disagree
Open questions, not settled findings — worth knowing before you cite any one of these.
Systems and scales differ across protein trafficking studies (species, tissues, methods), so mechanisms should not be over-generalised.
Common misconceptions
Protein trafficking 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 Protein trafficking?
Protein trafficking is the directed movement of proteins through cellular compartments to their functional destinations.
Why does Protein trafficking matter for biology undergraduates?
Where proteins go determines function — trafficking errors underlie many disease mechanisms taught in biology.
The studies
- Mapping the faces of mitochondria and ER
APEX2 proximity biotinylation yields high-quality proteomic maps of cytosol-facing outer mitochondrial and ER membranes in living human cells.
- How do proteins find plasmodesmata?
PDLP1 is a type I membrane protein targeted to plasmodesmata; altering PDLP dosage changes GFP cell-to-cell trafficking.
- What proteins build the caveolar coat?
Caveolins and cavins purify as a caveolar coat complex with Cavin 1 as a core trimeric component.
- SNARE timing in sperm acrosome exocytosis
Sperm acrosome exocytosis proceeds via ordered SNARE assembly/disassembly around intra-acrosomal Ca2+ release.
- How MC4R variants scramble receptor trafficking
Obesity-linked MC4R mutations disrupt plasma-membrane localization, endocytosis and β-arrestin pathways beyond classical cAMP loss-of-function.
- Spike glycosylation and palmitoylation trafficking
Glycosylation motifs and cysteine palmitoylation steer SARS-CoV-2 spike maturation, Golgi trafficking, and fusion.
- How does monoubiquitin turn down Rab5?
Rab5 is monoubiquitinated at specific lysines; ubiquitin at K140/K165 disrupts effector binding and downregulates endocytic trafficking.
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