Related Experiment Video
Updated: Feb 27, 2026
10:28
Preparation of Chloroplast Sub-compartments from Arabidopsis for the Analysis of Protein Localization by Immunoblotting or Proteomics
Published on: October 19, 2018
22.3K
Sorting of nuclear-encoded chloroplast membrane proteins
Dong Wook Lee1, Junho Lee2, Inhwan Hwang3
1Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang 37673, Republic of Korea.
Current Opinion in Plant Biology
|July 3, 2017
Summary
Targeting proteins to complex chloroplast membranes is challenging. This review details mechanisms for protein sorting to chloroplast envelope and thylakoid membranes.
Area of Science:
- Cell Biology
- Plant Biology
- Molecular Biology
Background:
- Chloroplasts possess intricate multi-membrane structures.
- Efficient protein targeting is crucial for chloroplast biogenesis and function.
- Understanding protein sorting to distinct chloroplast compartments remains a challenge.
Purpose of the Study:
- To review current knowledge on protein targeting mechanisms to chloroplast envelope and thylakoid membranes.
- To highlight the complexities of sorting nuclear-encoded proteins within chloroplasts.
- To identify future research directions in chloroplast protein targeting.
Main Methods:
- Review of existing literature on chloroplast protein biogenesis.
- Analysis of established and emerging protein targeting pathways.
- Comparative examination of sorting mechanisms for different chloroplast membranes.
Main Results:
- Direct targeting from cytosol to outer envelope membrane is possible.
- Inner envelope and thylakoid membrane targeting involves multi-step processes.
- These steps include cytosolic sorting, translocation, stromal sorting, and membrane insertion.
Conclusions:
- Protein targeting to chloroplasts, especially to internal membranes, is a complex, multi-step process.
- Distinct mechanisms govern protein sorting to the outer, inner envelope, and thylakoid membranes.
- Further research is needed to fully elucidate these intricate pathways.
Related Concept Videos
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
23.2K
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...
23.2K
01:34Nuclear Protein Sorting
6.5K
Nuclear protein sorting is the selective trafficking of histones, polymerases, gene regulatory proteins into the nucleus and exporting RNAs and ribosomes to the cytosol. It is a tightly controlled process that regulates gene expression within a cell.
Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
6.5K
01:18Protein Transport to the Inner Chloroplast Membrane
2.5K
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...
2.5K
01:11Protein Transport to the Outer Chloroplast Membrane
2.4K
Chloroplast outer membrane proteins encoded by the nucleus are synthesized in the cytosol. Soon after synthesis, they bind cytosolic factors such as 14-3-3 protein and the Hsp70 chaperones that keep these precursors in an unfolded state until their translocation.
Two models describe the mechanism of precursor recognition and entry across the outer membrane through the TOC complex. Model 1 suggests the newly synthesized precursor binds to the TOC receptor 159 and forms a complex.
Two models describe the mechanism of precursor recognition and entry across the outer membrane through the TOC complex. Model 1 suggests the newly synthesized precursor binds to the TOC receptor 159 and forms a complex.
2.4K
01:24Protein Transport to the Stroma
2.3K
Chloroplasts are triple membrane structures with an outer membrane, an inner membrane, and a thylakoid membrane, each containing distinct metabolite transporters, membrane translocons, and enzymes. Appropriate sorting and translocating these proteins to their correct membrane systems is essential for chloroplast function.
Protein complexes called the translocon of the outer chloroplast membrane or TOC complex, and the translocon of the inner chloroplast membrane or TIC complex mediate the...
Protein complexes called the translocon of the outer chloroplast membrane or TOC complex, and the translocon of the inner chloroplast membrane or TIC complex mediate the...
2.3K