Related Experiment Video
Updated: Mar 11, 2026
09:00
Cargo Loading onto Kinesin Powered Molecular Shuttles
Published on: November 3, 2010
11.0K
Shuttling and sorting lipid-modified cargo into the cilia.
Louise A Stephen1, Shehab Ismail1
1CR-UK Beatson Institute, Garscube Estate Switchback Road, Glasgow G61 1BD, U.K.
Biochemical Society Transactions
|December 3, 2016
Summary
Researchers identified a molecular machine that transports lipid-modified proteins to primary cilia, maintaining their unique composition. This mechanism involves specific solubilizing factors and the small G-protein Arl3 for cargo release within cilia.
Area of Science:
- Cell Biology
- Molecular Biology
- Organelle Biology
Background:
- Primary cilia are microtubule-based organelles present in most human cells.
- Cilia possess distinct molecular compositions, differing from the main cell body.
- Maintaining this unique ciliary composition is crucial for cellular function.
Purpose of the Study:
- To elucidate the molecular machinery responsible for shuttling and sorting proteins to primary cilia.
- To understand how the distinct composition of primary cilia is maintained.
Main Methods:
- Investigated the role of GDI-like solubilizing factors (UNC119a, UNC119b, PDE6D) in protein transport.
- Examined the function of the small G-protein Arl3 in cargo release within cilia.
- Studied the GTP-dependent mechanism of protein sorting.
Main Results:
- Identified a machinery involving UNC119a, UNC119b, and PDE6D that binds lipid-modified ciliary cargo.
- Demonstrated that the ciliary small G-protein Arl3 specifically releases cargo within the cilium.
- Characterized the GTP-dependent nature of this cargo release mechanism.
Conclusions:
- A novel molecular machinery facilitates the targeted delivery and sorting of lipid-modified proteins to primary cilia.
- This mechanism is essential for establishing and maintaining the unique molecular identity of cilia.
- The interplay between solubilizing factors and Arl3 is key to ciliary protein homeostasis.
Related Concept Videos
01:12Clathrin Coated Vesicles
9.9K
Clathrin-coated vesicles use endocytosis to transport receptors and lysosomal hydrolases from the Golgi to the lysosome in the late secretory pathway. Clathrin-mediated endocytosis was the first described endocytic process, and Clathrin-coated vesicles remain one of the most well-studied transport vesicles. The molecular machinery that generates clathrin-coated vesicles comprises over 50 proteins that precisely coordinate vesicle formation. Cell surface receptors concentrated in indented sites...
9.9K
00:59COP Coated Vesicles
18.5K
Membrane-enclosed structures called vesicles transport proteins and lipids across the cell. The vesicles derive their cargo from the plasma membrane, Golgi, ER, or endosome. Coated vesicles are spherical, protein-coated carriers with a 50–100 nm diameter that mediate bidirectional transport between the ER and the Golgi. The distribution of proteins between the ER and Golgi complex is dynamic and is maintained by different coated vesicles. Their formation is driven by the assembly of...
18.5K
01:05Mechanism of Ciliary Motion
5.5K
The ciliary structures were first seen in 1647 by Antonie Leeuwenhoek while observing the protozoans. In lower organisms, these appendages are responsible for cell movement, while in higher organisms, these appendages help in the movement of the extracellular fluids within the body cavities.
The cilia are made up of microtubules in a 9+2 arrangement, with nine microtubule doublet ring bundles, surrounding a pair of central singlet microtubule bundles. The doublet microtubule bundles are...
The cilia are made up of microtubules in a 9+2 arrangement, with nine microtubule doublet ring bundles, surrounding a pair of central singlet microtubule bundles. The doublet microtubule bundles are...
5.5K
01:39Mitochondrial Protein Sorting
5.9K
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...
5.9K
01:45Overview of Protein Sorting and Transport
23.3K
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...
23.3K
01:44Introduction to Membrane Traffic
10.0K
The ER, Golgi apparatus, endosomes, and lysosomes work in tandem to modify, sort, and package proteins and lipids. An integrated membrane trafficking network facilitates the back and forth shuttling of molecules within different organelles in the same cell or across the cell membrane.
The transport of soluble and membrane proteins is mediated by transport vesicles that collect cargo from one cellular compartment and deliver it to another by fusing with the target organelle membrane. The Rab...
The transport of soluble and membrane proteins is mediated by transport vesicles that collect cargo from one cellular compartment and deliver it to another by fusing with the target organelle membrane. The Rab...
10.0K