GO:0006614 SRP-dependent cotranslational protein targeting to membrane: Protein Synthesis Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0006614 describes the co-translational delivery of nascent proteins to the endoplasmic reticulum membrane, requiring the signal recognition particle (SRP) and its receptor.
• The process is conserved from bacteria to humans, with bacterial SRP (Ffh) and FtsY serving as models for the eukaryotic SRP and SRP receptor.
• SRP binds the signal sequence of a nascent polypeptide as it emerges from the ribosome, pauses translation, and targets the ribosome-nascent chain complex to the membrane.
• Defects in SRP-dependent targeting are linked to diseases such as coronary artery disease and cancer, as shown by macrophage gene-regulatory networks.
• Experimental approaches include ribosome profiling, proteomics, and CRISPR-based knockout or knock-in models to dissect gene function.
• EDITGENE provides CRISPR services to create knockout, point-mutation, knock-in, and overexpression cell models for studying this pathway.
Description
The signal recognition particle (SRP)-dependent co-translational protein targeting to membrane (GO:0006614) is a fundamental cellular process that ensures newly synthesized proteins destined for the secretory pathway are correctly delivered to the endoplasmic reticulum (ER) membrane. This pathway is essential for the biogenesis of membrane and secreted proteins, and its dysfunction is associated with a range of human diseases. Understanding the molecular details of this process is critical for researchers in cell biology, biochemistry, and drug discovery. The mechanism is highly conserved across all domains of life, with bacterial systems providing key structural and mechanistic insights. In this article, we provide a comprehensive overview of GO:0006614, covering its definition, key genes, regulatory mechanisms, disease relevance, and experimental models for study.
SRP-dependent cotranslational protein targeting to membrane At A Glance
| GO ID | GO:0006614 |
|---|---|
| GO term | SRP-dependent cotranslational protein targeting to membrane |
| Ontology | biological_process |
| Synonym | ER translocation; SRP-dependent cotranslational membrane targeting; SRP-dependent cotranslational protein-membrane targeting |
| Major function | Targeting nascent proteins to the ER membrane during translation |
| Key components | Signal recognition particle (SRP), SRP receptor, ribosome, nascent polypeptide |
| Cellular location | Cytosol and endoplasmic reticulum membrane |
| Conservation | Conserved from bacteria to humans |
What Is GO:0006614?
GO:0006614, SRP-dependent cotranslational protein targeting to membrane, is defined as the targeting of proteins to a membrane that occurs during translation and depends on two key components: the signal-recognition particle (SRP) and the SRP receptor. SRP is a cytosolic ribonucleoprotein that transiently binds to the ER signal sequence in a nascent protein, to the large ribosomal subunit, and to the SRP receptor in the ER membrane. This process ensures that proteins with an N-terminal signal peptide are delivered to the ER membrane while still being synthesized, allowing their subsequent translocation into the ER lumen or insertion into the membrane.
Why Is SRP-dependent cotranslational protein targeting to membrane Important in Cell Biology?
SRP-dependent co-translational targeting is essential for the proper localization of approximately one-third of the proteome, including secreted proteins, membrane receptors, and lysosomal enzymes. Defects in this pathway can lead to protein misfolding, ER stress, and various diseases, including cancer and cardiovascular disorders. Moreover, the pathway is a target for antibiotics and is being explored for therapeutic interventions. Understanding its regulation and components is therefore of broad biomedical importance.
• Essential for the biogenesis of secretory and membrane proteins.
• Conserved mechanism across bacteria, archaea, and eukaryotes.
• Dysregulation linked to coronary artery disease and macrophage dysfunction.
• Plays a role in topogenesis of membrane proteins, as shown for Spc3.
• Tail-anchored proteins can use alternative pathways, highlighting the specificity of SRP-dependent targeting.
• Target for novel antibiotics and cancer therapeutics.
• Key to understanding ER stress and unfolded protein response.
• Provides a model for studying protein targeting and translocation.
• Involved in immune cell function and inflammation.
• Experimental models enable dissection of gene function in health and disease.
What Happens During SRP-dependent cotranslational protein targeting to membrane?
Signal Sequence Recognition by SRP
In simple terms: SRP grabs the signal sequence of a new protein as it comes out of the ribosome.
As a nascent polypeptide emerges from the ribosomal exit tunnel, the signal recognition particle (SRP) binds to its N-terminal signal sequence. This interaction is mediated by the SRP54 subunit in eukaryotes or Ffh in bacteria. Structural studies have revealed that SRP undergoes a conformational change upon binding, allowing it to interact with the ribosome and pause translation. This step ensures that only proteins with a correct signal sequence are targeted to the ER membrane.
Targeting to the ER Membrane
In simple terms: The SRP-ribosome complex moves to the ER membrane and docks onto the SRP receptor.
The SRP-ribosome-nascent chain complex is directed to the ER membrane through the interaction of SRP with the SRP receptor (SRα in eukaryotes, FtsY in bacteria). This docking is GTP-dependent and leads to the release of the signal sequence from SRP and its transfer to the translocon channel. In bacteria, this step has been dissected as a separate event from SecA-dependent translocation.
Translation and Translocation
In simple terms: The protein continues to be made and is threaded into the ER membrane.
Once the ribosome is docked at the translocon, translation resumes, and the growing polypeptide chain is co-translationally translocated into the ER lumen or inserted into the membrane. The signal peptide is cleaved by signal peptidase, and the protein folds in the ER. This process is tightly coupled to translation and requires GTP hydrolysis by both SRP and SRP receptor.
Cooperation with Posttranslational Pathways
In simple terms: Some proteins can use both co-translational and posttranslational routes.
Recent studies have shown that co-translational targeting can cooperate with posttranslational translocation for certain proteins, such as Spc3 in yeast. This flexibility ensures efficient membrane protein topogenesis even under stress conditions. Additionally, tail-anchored proteins can use SRP-independent pathways, highlighting the diversity of membrane targeting mechanisms.
Key Genes Involved in GO:0006614 SRP-dependent cotranslational protein targeting to membrane
The following genes and proteins are core components or regulators of SRP-dependent co-translational protein targeting to membrane.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SRP54 | Signal sequence binding subunit of SRP | Key for substrate recognition; mutations linked to diseases |
| SRP9 | Component of SRP Alu domain | Involved in translation arrest |
| SRP14 | Component of SRP Alu domain | Involved in translation arrest |
| SRP19 | Binds SRP RNA | Required for SRP assembly |
| SRP68 | Component of SRP S domain | Facilitates SRP RNA binding |
| SRP72 | Component of SRP S domain | Facilitates SRP RNA binding |
| SRPR | SRP receptor alpha subunit | Docks SRP at ER membrane |
| SRPRB | SRP receptor beta subunit | Anchors SRP receptor to membrane |
| FTSY | Bacterial SRP receptor | Model for SRP receptor function |
| FFH | Bacterial SRP protein | Model for SRP function |
| SEC61A1 | Translocon subunit | Protein translocation channel |
| SEC61B | Translocon subunit | Protein translocation channel |
| SEC61G | Translocon subunit | Protein translocation channel |
| SPCS1 | Signal peptidase subunit | Cleaves signal peptide |
| SPCS2 | Signal peptidase subunit | Cleaves signal peptide |
| SPCS3 | Signal peptidase subunit | Cleaves signal peptide |
| SPC3 | Membrane protein topogenesis | Cooperation with posttranslational pathways |
| GET3 | Tail-anchored protein targeting | Alternative pathway |
How Is SRP-dependent cotranslational protein targeting to membrane Regulated?
The SRP-dependent co-translational targeting pathway is regulated at multiple levels. Translation elongation is temporarily paused upon SRP binding to the ribosome, which is relieved upon interaction with the SRP receptor. GTP binding and hydrolysis by SRP and SRP receptor control the cycle of targeting and release. Additionally, cellular stress conditions, such as ER stress, can upregulate components of the pathway to meet increased demand for protein folding. In macrophages, gene-regulatory networks involving SRP components have been linked to coronary artery disease severity, suggesting that inflammatory signaling may influence this pathway.
SRP-dependent cotranslational protein targeting to membrane and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SRP54 | Ribosomopathy, neutropenia | Knockout cell lines, patient-derived iPSCs |
| SRPR | ER stress-related disorders | Point mutation knock-in in HEK293 |
| SEC61A1 | Tubulointerstitial kidney disease | Knock-in mouse models |
| SPC3 | Membrane protein topogenesis defects | Yeast knockout and overexpression |
| GET3 | Tail-anchored protein mislocalization | Knockout in plant models |
Coronary Artery Disease
A macrophage gene-regulatory network linked to clinical severity of coronary artery disease has been identified, implicating SRP-dependent targeting components. This suggests that dysregulation of co-translational targeting in immune cells may contribute to atherosclerosis and cardiovascular risk.
Cancer
Altered expression of SRP subunits and translocon components has been observed in various cancers, where increased secretory activity supports tumor growth and metastasis. Targeting this pathway may offer therapeutic opportunities.
Ribosomopathies and ER Stress
Mutations in SRP components can lead to ribosomopathies and ER stress-related disorders, as the pathway is essential for protein homeostasis. Defects in co-translational targeting can cause accumulation of misfolded proteins and activate the unfolded protein response.
From SRP-dependent cotranslational protein targeting to membrane-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does SRP54 loss affect secretory protein targeting? | CRISPR knockout in HeLa or HEK293 cells |
| Does a point mutation in SRPR alter GTP hydrolysis? | Point mutation knock-in in cell lines |
| Can a tagged SRP54 be used for live imaging? | Knock-in of fluorescent tag (e.g., GFP) at endogenous locus |
| Does overexpression of SRP components enhance secretion? | Overexpression cell lines |
| Which genes interact with SRP pathway in macrophages? | CRISPR library screening in macrophage cell lines |
| Is Spc3 topogenesis dependent on SRP? | Yeast knockout and overexpression |
How to Study the SRP-dependent cotranslational protein targeting to membrane Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Ribo-seq | Ribosome occupancy and translation pausing | Global analysis of co-translational targeting |
| Proteomics | Protein abundance and secretion | Identifying substrates and pathway defects |
| Fluorescence microscopy | Localization and dynamics of SRP components | Live-cell imaging of targeting |
| CRISPR knockout screening | Gene essentiality and pathway regulators | Discovery of novel components |
| Co-immunoprecipitation | Protein-protein interactions | Studying SRP-ribosome complexes |
| In vitro translation | Targeting and translocation efficiency | Mechanistic studies |
| GTPase assays | GTP hydrolysis by SRP and SRP receptor | Kinetic analysis |
| Electron microscopy | Structural details of targeting complex | High-resolution structures |
Ribosome Profiling (Ribo-seq)
Ribo-seq allows genome-wide mapping of ribosome positions and can reveal translation pausing induced by SRP binding. It is used to study co-translational targeting efficiency and identify substrates.
Proteomics and Secretome Analysis
Mass spectrometry-based proteomics can quantify secreted and membrane proteins to assess the impact of perturbations in SRP-dependent targeting. This approach identifies proteins whose localization depends on the pathway.
Fluorescence Imaging
Live-cell imaging of fluorescently tagged SRP components or nascent chains can visualize targeting events in real time. This method is useful for studying dynamics and localization.
CRISPR Screening
Genome-wide CRISPR knockout or activation screens can identify genes that modulate SRP-dependent targeting, as demonstrated in macrophage studies. This unbiased approach reveals novel regulators and disease links.
How CRISPR Can Be Used to Study GO:0006614 SRP-dependent cotranslational protein targeting to membrane
Knockout
CRISPR knockout of SRP components (e.g., SRP54, SRPR) can abolish co-translational targeting, leading to defects in secretory protein biogenesis. Such models are valuable for studying the pathway's role in cell viability and disease.
Point Mutation
Introducing point mutations in GTP-binding motifs of SRP54 or SRPR can dissect the GTPase cycle and its role in targeting. These models help understand disease-associated mutations.
Knock-in
Knock-in of fluorescent tags (e.g., GFP) at endogenous loci allows real-time imaging of SRP components without overexpression artifacts. This approach is useful for studying dynamics and localization.
Overexpression
Overexpression of SRP subunits or SRP receptor can enhance targeting efficiency and secretion, providing models to study pathway saturation and regulation.
How EDITGENE Supports SRP-dependent cotranslational protein targeting to membrane Research
Researchers studying SRP-dependent cotranslational protein targeting to membrane-related genes often need to determine whether a candidate gene is causally involved in the pathway or in disease. EDITGENE provides comprehensive CRISPR services to create precisely engineered cell models, enabling functional validation and mechanistic studies.
Contact EDITGENE today to design your custom CRISPR model for SRP-dependent cotranslational protein targeting to membrane research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SRPRA Knockout HEK293 Cell Line | EDJ-KQ5092 | Human | 6734 | Details Get a Quote |
| SSR3 Knockout HEK293 Cell Line | EDJ-KQ5847 | Human | 6747 | Details Get a Quote |
| SRPRA Knockout A-549 Cell Line | EDJ-KQ29297 | Human | 6734 | Details Get a Quote |
| SRPRA Knockout HCT 116 Cell Line | EDJ-KQ29298 | Human | 6734 | Details Get a Quote |
| SRPRA Knockout HeLa Cell Line | EDJ-KQ29299 | Human | 6734 | Details Get a Quote |
| SSR3 Knockout A-549 Cell Line | EDJ-KQ29309 | Human | 6747 | Details Get a Quote |
| SSR3 Knockout HCT 116 Cell Line | EDJ-KQ29310 | Human | 6747 | Details Get a Quote |
| SSR3 Knockout HeLa Cell Line | EDJ-KQ29311 | Human | 6747 | Details Get a Quote |
| SRP9 Knockout HEK293 Cell Line | EDJ-KQ50657 | Human | 6726 | Details Get a Quote |
| SRP14 Knockout HEK293 Cell Line | EDJ-KQ50658 | Human | 6727 | Details Get a Quote |
| SRP9 Knockout HeLa Cell Line | EDJ-KQ54564 | Human | 6726 | Details Get a Quote |
| SRP14 Knockout HeLa Cell Line | EDJ-KQ54565 | Human | 6727 | Details Get a Quote |
| SRP9 Knockout A-549 Cell Line | EDJ-KQ63048 | Human | 6726 | Details Get a Quote |
| SRP14 Knockout A-549 Cell Line | EDJ-KQ63049 | Human | 6727 | Details Get a Quote |
| SRP9 Knockout HCT 116 Cell Line | EDJ-KQ71522 | Human | 6726 | Details Get a Quote |
Displaying Records 1 To 15 Of 16 Records
Frequently Asked Questions About SRP-dependent cotranslational protein targeting to membrane
What is SRP-dependent cotranslational protein targeting to membrane?
It is the process by which nascent proteins with a signal sequence are targeted to the ER membrane during translation, mediated by the signal recognition particle (SRP) and its receptor.
What genes are involved in SRP-dependent cotranslational protein targeting?
Key genes include SRP54, SRP9, SRP14, SRP19, SRP68, SRP72, SRPR, SRPRB, and the translocon components SEC61A1, SEC61B, SEC61G.
What is the role of SRP in protein targeting?
SRP binds to the signal sequence of nascent proteins, pauses translation, and targets the ribosome-nascent chain complex to the ER membrane via the SRP receptor.
How is SRP-dependent targeting regulated?
It is regulated by GTP binding and hydrolysis by SRP and SRP receptor, and by cellular stress conditions that upregulate pathway components.
What diseases are associated with defects in SRP-dependent targeting?
Defects have been linked to coronary artery disease, cancer, and ribosomopathies.
What experimental models are used to study this pathway?
Common models include CRISPR knockout cell lines, point mutation knock-ins, tagged knock-ins, and overexpression lines, as well as yeast and bacterial systems.
Can CRISPR be used to study SRP-dependent targeting?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are powerful tools to dissect gene function in this pathway.
What is the difference between co-translational and posttranslational targeting?
Co-translational targeting occurs during translation and requires SRP, while posttranslational targeting occurs after translation and can involve other chaperones.
How can I measure SRP-dependent targeting efficiency?
Methods include ribosome profiling, proteomics, and in vitro translation assays.
What services does EDITGENE offer for studying this pathway?
EDITGENE provides CRISPR knockout, point mutation, knock-in, overexpression cell models, library screening, and bioinformatics analysis.
Conclusion
SRP-dependent cotranslational protein targeting to membrane (GO:0006614) is a cornerstone of protein biogenesis and cellular homeostasis. Its dysregulation is implicated in cardiovascular disease, cancer, and other disorders. By leveraging CRISPR-based models and advanced omics technologies, researchers can uncover new insights into this pathway and develop targeted therapies. EDITGENE offers a comprehensive suite of services to accelerate such research.
References
- 1. Steinberg R et al.. 2018. Co-translational protein targeting in bacteria.. FEMS Microbiol Lett 365(11) PMID: 29790984
- 2. von Loeffelholz O et al.. 2015. Ribosome-SRP-FtsY cotranslational targeting complex in the closed state.. Proc Natl Acad Sci U S A 112(13):3943-8 PMID: 25775537
- 4. Neumann-Haefelin C et al.. 2000. SRP-dependent co-translational targeting and SecA-dependent translocation analyzed as individual steps in the export of a bacterial protein.. EMBO J 19(23):6419-26 PMID: 11101515
- 5. Egea PF et al.. 2005. Targeting proteins to membranes: structure of the signal recognition particle.. Curr Opin Struct Biol 15(2):213-20 PMID: 15837181
- 6. Jung SJ et al.. 2021. Cotranslational Targeting and Posttranslational Translocation can Cooperate in Spc3 Topogenesis.. J Mol Biol 433(18):167109 PMID: 34153287
- 7. Mehlhorn DG et al.. 2021. Looking for a safe haven: tail-anchored proteins and their membrane insertion pathways.. Plant Physiol 187(4):1916-1928 PMID: 35235667
- 8. Ma L et al.. 2025. A macrophage gene-regulatory network linked to clinical severity of coronary artery disease : The STARNET and NGS-PREDICT primary blood macrophage studies.. Basic Res Cardiol 120(4):799-814 PMID: 40590916
