Related Experiment Video
Updated: May 8, 2026
12:15
In Vitro Polymerization of F-actin on Early Endosomes
Published on: August 28, 2017
Sequential intermediates in the pathway of intercompartmental transport in a cell-free system
Cell
|December 1, 1984
Summary
Researchers identified three key steps in the transport of vesicular stomatitis virus glycoprotein (G protein) within the Golgi apparatus. These steps involve membrane priming, G protein transfer, and fusion, likely corresponding to vesicle budding and fusion processes.
Area of Science:
- Cell Biology
- Virology
- Molecular Biology
Background:
- The transport of viral glycoproteins within the Golgi apparatus is crucial for viral assembly and infectivity.
- Understanding the precise mechanisms of protein trafficking in the Golgi is essential for deciphering cellular processes.
Purpose of the Study:
- To elucidate the distinct stages involved in the transport of the vesicular stomatitis virus glycoprotein (G protein) between Golgi compartments.
- To investigate the role of vesicle budding and fusion in G protein trafficking.
Main Methods:
- Utilized two-stage incubations to analyze transport steps.
- Employed N-ethylmaleimide to selectively inhibit and differentiate transport stages.
- Conducted electron microscopy to visualize membrane dynamics and vesicle formation.
Main Results:
- Identified three sequential steps: priming, transfer, and fusion of G protein.
- Observed the formation of small vesicles (60-80 nm) during the priming stage, budding from Golgi cisternae rims.
- Demonstrated that priming makes G protein available for transfer, leading to a prefusion complex before final delivery.
Conclusions:
- The three identified steps (priming, transfer, fusion) likely represent distinct phases of transport vesicle budding and fusion.
- This study provides a working hypothesis for the mechanistic basis of G protein transport within the Golgi.
Related Concept Videos
00:58Recycling Endosomes and Transcytosis
The recycling endosome, also known as the endosomal recycling compartment (ERC), is a part of the slow-recycling process of the endocytic pathway. Molecules internalized through receptor-mediated endocytosis are either degraded in the lysosomes or are recycled to the plasma membrane through the fast- or slow-recycling route.
The recycling endosome is not a single organelle but an extensively tubulated network of recycling pathways. It functions in storing molecules or transporting them across...
The recycling endosome is not a single organelle but an extensively tubulated network of recycling pathways. It functions in storing molecules or transporting them across...
01:45Overview of Protein Sorting and Transport
Eukaryotic cells have different membrane-bound organelles with distinct protein requirements. The process by which proteins are targeted to a specific organelle is called protein sorting.
Protein sorting can be of two types: signal-based sorting and vesicle-based trafficking. In signal-based sorting, specific amino acid sequences called sorting signals target proteins to the proper location inside the cell either via gated transport or by protein translocation. In gated transport, folded...
Protein sorting can be of two types: signal-based sorting and vesicle-based trafficking. In signal-based sorting, specific amino acid sequences called sorting signals target proteins to the proper location inside the cell either via gated transport or by protein translocation. In gated transport, folded...
01:39Mitochondrial Protein Sorting
Mitochondria are double-membrane organelles of the eukaryotes involved in cellular metabolism, signaling, ATP synthesis, and programmed cell death. Each of these processes requires specific proteins and enzymes that must be correctly sorted to the right mitochondrial subcompartment for the proper functioning of the organelle.
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
01:19Translocation of Proteins into the Mitochondria
Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
01:34Protein Transport into the Inner Mitochondrial Membrane
Nuclear encoded mitochondrial precursors are imported to the inner membrane in a multistep process involving two separate translocons, TIM22 and TIM23. TIM23 is a cation-selective pore that remains closed by the N terminal segment of the protein. Negative charges on the TIM23 act as a receptor for the incoming precursor, pulling the positively charged matrix-targeting sequence for peptide insertion and translocation.
Transport of mitochondrial precursors across the TIM23 channel is driven by...
Transport of mitochondrial precursors across the TIM23 channel is driven by...
01:18Protein Transport to the Inner Chloroplast Membrane
Proteins targeted to the inner chloroplast membrane, or plastid proteins, are transported by two general pathways: the stop-transfer and the re-insertion or post-import pathways. Most plastid proteins carry N-terminal transit sequences and internal import sequences targeting it to the specific chloroplast subcompartment. Proteins targeted by the stop-transfer pathway have internal hydrophobic sequences that inhibit their translocation into the stroma. As a result, these precursors are arrested...