GO:0045309 protein phosphorylated amino acid binding: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0045309 (protein phosphorylated amino acid binding) is a molecular function defined as binding to a phosphorylated amino acid residue within a protein [QuickGO definition].
• This activity is central to signal transduction, allowing modular domains such as SH2 and PTB to recognize phosphotyrosine and transduce signals from receptor tyrosine kinases.
• Key proteins include the Rag GTPases, which bind to phosphorylated amino acids to mediate amino acid signaling to mTORC1 [1,2].
• Dysregulation of phospho-amino-acid binding is implicated in cancer, metabolic disorders, and neurodegeneration.
• CRISPR knockout, point mutation, and knock-in models enable precise interrogation of phospho-binding interfaces.
• Methods such as Ribo-seq, proteomics, and imaging are used to study the functional consequences of phospho-binding [3,4].
Description
Protein phosphorylated amino acid binding (GO:0045309) is a molecular function that enables a protein to selectively recognize and bind to phosphorylated amino acid residues within another protein [QuickGO definition]. This activity is fundamental to cellular signal transduction, as it allows the cell to decode phosphorylation marks into specific biological responses. For example, the binding of the Rag GTPases to phosphorylated amino acids is critical for amino acid sensing and mTORC1 activation. Similarly, the adaptor protein c-Crk binds to tyrosine-phosphorylated proteins through its SH2 domain, a classic example of this function. Understanding this term is essential for researchers studying signal transduction, because it defines how phosphorylation signals are interpreted by downstream effectors. Moreover, mutations that disrupt phospho-amino-acid binding can lead to diseases such as cancer and neurodegeneration. Thus, GO:0045309 provides a framework for investigating the molecular basis of phosphorylation-dependent interactions.
protein phosphorylated amino acid binding At A Glance
| GO ID | GO:0045309 |
|---|---|
| GO term | protein phosphorylated amino acid binding |
| Ontology | molecular_function |
| Synonym | phosphoprotein amino acid binding |
| Major function | Binding to a phosphorylated amino acid residue within a protein |
| Definition source | QuickGO |
| Related activity | Signal transduction, protein complex assembly |
| Example proteins | Rag GTPases, c-Crk, SMN, PTEN |
What Is GO:0045309?
According to the Gene Ontology, GO:0045309 (protein phosphorylated amino acid binding) is defined as the binding to a phosphorylated amino acid residue within a protein. This function is mediated by specialized protein modules that recognize phosphoserine, phosphothreonine, or phosphotyrosine residues in the context of a polypeptide chain. It is a molecular function that underlies many signaling pathways, enabling the assembly of protein complexes and the propagation of signals from kinases to downstream effectors.
Why Is protein phosphorylated amino acid binding Important in Cell Biology?
Protein phosphorylated amino acid binding is a cornerstone of cellular signaling, as it allows the cell to translate phosphorylation events into specific functional outcomes. This activity is essential for processes such as nutrient sensing, cell growth, and stress responses [1,3]. Dysregulation of this binding can lead to a variety of diseases, including cancer, where aberrant phospho-binding can drive uncontrolled proliferation. Therefore, understanding the molecular details of this function is critical for both basic research and therapeutic development.
• Enables signal transduction from receptor tyrosine kinases to downstream pathways.
• Mediates amino acid sensing and mTORC1 activation via Rag GTPases [1,2].
• Regulates translation initiation under stress conditions through GCN2 and eIF2α.
• Involved in lysosomal signaling and autophagy regulation.
• Mutations in phospho-binding domains are linked to cancer and neurodegeneration.
• Provides targets for drug discovery, especially in oncology.
• Facilitates the study of protein-protein interactions using phospho-specific probes.
• Essential for understanding cellular responses to growth factors and nutrients [1,4].
Molecular Mechanism of protein phosphorylated amino acid binding
Recognition of Phosphorylated Residues
In simple terms: The binding protein has a pocket that fits a phosphate group attached to an amino acid.
The initial step in protein phosphorylated amino acid binding involves the specific recognition of a phosphorylated residue, typically phosphotyrosine, phosphoserine, or phosphothreonine. This recognition is mediated by modular domains such as SH2, PTB, or 14-3-3, which contain a conserved binding pocket that coordinates the phosphate group through hydrogen bonds and electrostatic interactions. For example, the SH2 domain of c-Crk binds to tyrosine-phosphorylated proteins with high specificity.
Conformational Changes and Complex Assembly
In simple terms: Binding causes the protein to change shape and assemble with other proteins.
Upon binding to a phosphorylated amino acid, the binding protein often undergoes conformational changes that expose interaction surfaces, leading to the assembly of multi-protein complexes. This is exemplified by the Rag GTPases, which bind to phosphorylated amino acids and recruit mTORC1 to the lysosomal membrane [1,2]. The formation of such complexes is essential for propagating signals and executing cellular responses.
Regulation by Phosphorylation State
In simple terms: The binding only happens when the target protein is phosphorylated.
The interaction is tightly regulated by the phosphorylation state of the target protein, which is controlled by the opposing activities of kinases and phosphatases. For instance, the binding of c-Crk to tyrosine-phosphorylated proteins is dependent on the phosphorylation of specific tyrosine residues. This dynamic regulation ensures that signals are transient and reversible.
Downstream Signaling and Functional Outputs
In simple terms: Once bound, the protein triggers a cascade of events inside the cell.
The binding event initiates downstream signaling cascades that can lead to changes in gene expression, metabolism, or cell growth. For example, the binding of Rag GTPases to phosphorylated amino acids activates mTORC1, which promotes protein synthesis and cell growth [1,2]. Similarly, the binding of GCN2 to phosphorylated eIF2α regulates translation initiation under stress.
Key Genes Involved in GO:0045309 protein phosphorylated amino acid binding
The following genes encode proteins that either exhibit protein phosphorylated amino acid binding activity or are key components of the pathways in which this function is critical.
| Gene | Major Role | Research Relevance |
|---|---|---|
| RRAGA | Rag GTPase that binds phosphorylated amino acids to mediate mTORC1 signaling | Amino acid sensing, cancer metabolism |
| RRAGB | Rag GTPase paralog involved in mTORC1 activation | Nutrient signaling, lysosomal function |
| RRAGC | Rag GTPase that binds phosphorylated amino acids | mTORC1 regulation, autophagy |
| RRAGD | Rag GTPase involved in amino acid-dependent mTORC1 activation | Metabolic disorders |
| CRK | Adaptor protein with SH2 domain that binds phosphotyrosine | Signal transduction, cancer |
| SMN1 | Survival motor neuron protein, binds PTEN in a phosphorylation-dependent manner | Spinal muscular atrophy |
| PTEN | Phosphatase that can be regulated by phospho-binding | Cancer, tumor suppression |
| GCN2 | Kinase that binds phosphorylated eIF2α | Stress response, translation control |
| EIF2AK4 | GCN2 kinase, involved in amino acid sensing | Integrated stress response |
| TBK1 | Kinase that responds to amino acid availability and regulates mTORC1 | Lysosomal signaling, autophagy |
| RAB7 | GTPase involved in lysosomal function, regulated by TBK1 | Membrane trafficking |
| YIH1 | Actin-binding protein that inhibits GCN2 | Amino acid control |
| LAMTOR1 | Component of Ragulator complex, required for Rag GTPase function | mTORC1 activation |
| LAMTOR2 | Ragulator component, involved in lysosomal mTORC1 signaling | Nutrient sensing |
| LAMTOR3 | Ragulator component, essential for Rag GTPase recruitment | mTORC1 pathway |
| LAMTOR4 | Ragulator component, part of the pentameric complex | Lysosomal signaling |
| LAMTOR5 | Ragulator component, stabilizes the complex | mTORC1 regulation |
How Is protein phosphorylated amino acid binding Regulated?
Protein phosphorylated amino acid binding is regulated by the phosphorylation state of target proteins, which is controlled by kinases and phosphatases. For example, the binding of c-Crk to tyrosine-phosphorylated proteins is dependent on the activity of tyrosine kinases. Additionally, the availability of amino acids regulates the binding of Rag GTPases to phosphorylated amino acids, which in turn controls mTORC1 signaling [1,2]. The lysosomal TBK1 kinase responds to amino acid availability to relieve Rab7-dependent inhibition of mTORC1, further illustrating the regulatory complexity. Moreover, the integrated stress response kinase GCN2 binds to phosphorylated eIF2α to modulate translation initiation under stress.
protein phosphorylated amino acid binding and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| PTEN | Cancer, tumor suppression | Knockout and point mutation models in cancer cell lines |
| SMN1 | Spinal muscular atrophy | Knock-in of patient mutations in iPSCs |
| CRK | Cancer, signal transduction | Overexpression and knockout in fibroblasts |
| RRAGA | Metabolic disorders, cancer | Knockout in HEK293T cells |
| TBK1 | Neurodegeneration, autophagy | Knockout in neuronal cells |
Cancer
Dysregulation of protein phosphorylated amino acid binding is frequently observed in cancer. For instance, mutations in the PTEN gene that affect its phospho-binding properties can lead to aberrant activation of the PI3K/AKT pathway, promoting tumorigenesis. Similarly, the SH2 domain of c-Crk, which binds phosphotyrosine, is involved in oncogenic signaling. Targeting these interactions is a promising therapeutic strategy.
Neurodegeneration
In neurodegenerative diseases such as spinal muscular atrophy (SMA), the survival motor neuron protein SMN1 binds to PTEN in a phosphorylation-dependent manner, and disruption of this interaction contributes to disease pathology. This highlights the importance of phospho-amino-acid binding in neuronal survival.
Metabolic Disorders
The Rag GTPases, which bind phosphorylated amino acids to activate mTORC1, are critical for metabolic homeostasis. Dysregulation of this pathway is linked to obesity, diabetes, and cancer metabolism [1,2]. Understanding the molecular details of these interactions may lead to new treatments for metabolic diseases.
From protein phosphorylated amino acid binding-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does knockout of RRAGA affect mTORC1 signaling? | CRISPR knockout in HEK293T cells |
| How does point mutation in the SH2 domain of CRK affect phosphotyrosine binding? | Point mutation knock-in in cancer cell lines |
| Can knock-in of a phospho-mimetic mutation in SMN1 rescue SMA phenotypes? | Knock-in in iPSC-derived motor neurons |
| What is the effect of overexpression of YIH1 on GCN2 activity? | Overexpression in yeast or mammalian cells |
| How does tagged knock-in of RRAGC affect lysosomal localization? | Tagged knock-in in HeLa cells |
| Does knockout of TBK1 alter lysosomal mTORC1 signaling? | Knockout in mouse embryonic fibroblasts |
How to Study the protein phosphorylated amino acid binding Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Ribo-seq | Translation efficiency | Studying stress-induced translation |
| Phosphoproteomics | Phosphorylation sites and binding partners | Mapping signaling networks |
| Co-immunoprecipitation | Protein-protein interactions | Validating phospho-dependent binding |
| Fluorescence microscopy | Subcellular localization | Visualizing mTORC1 recruitment |
| CRISPR knockout | Gene function | Identifying essential genes |
| CRISPR activation | Gene overexpression | Studying gain-of-function |
| Yeast two-hybrid | Binary interactions | Screening for phospho-binding domains |
Ribosome Profiling (Ribo-seq)
Ribo-seq measures translation efficiency at codon resolution. It can be used to study how protein phosphorylated amino acid binding affects translation initiation, for example, by monitoring the integrated stress response.
Proteomics and Phosphoproteomics
Mass spectrometry-based proteomics can identify proteins that bind to phosphorylated amino acids and quantify changes in phosphorylation states. This is useful for mapping signaling networks involving Rag GTPases and mTORC1 [1,2].
Imaging and Live-Cell Analysis
Fluorescence microscopy can visualize the localization and dynamics of phospho-binding proteins, such as the recruitment of mTORC1 to the lysosome [2,4].
CRISPR Screening
Genome-wide CRISPR screens can identify genes that regulate phospho-amino-acid binding and downstream pathways. This approach is powerful for discovering novel components of signaling networks.
How CRISPR Can Be Used to Study GO:0045309 protein phosphorylated amino acid binding
Knockout
CRISPR knockout is used to eliminate the expression of genes encoding phospho-binding proteins, such as RRAGA or CRK, to study their loss-of-function phenotypes. For example, knockout of RRAGA in HEK293T cells abolishes mTORC1 activation in response to amino acids.
Point Mutation
Point mutations can be introduced to disrupt the phospho-binding interface, such as mutating the critical arginine in the SH2 domain of CRK. This allows researchers to dissect the specific contribution of phospho-binding to signaling.
Knock-in
Knock-in of phospho-mimetic or phospho-deficient mutations can mimic or prevent phosphorylation, respectively. For instance, knock-in of a phospho-mimetic mutation in SMN1 can rescue PTEN binding and stability.
Overexpression
Overexpression of phospho-binding proteins, such as YIH1, can be used to study gain-of-function effects, including inhibition of GCN2 and impairment of general amino acid control.
How EDITGENE Supports protein phosphorylated amino acid binding Research
Researchers studying protein phosphorylated amino acid binding-related genes often need to determine whether a candidate gene is causally involved in a specific signaling pathway or disease. EDITGENE provides a comprehensive suite of CRISPR services to enable precise genetic manipulation and functional interrogation.
Contact EDITGENE today to design your custom CRISPR model for protein phosphorylated amino acid binding research.
Frequently Asked Questions About protein phosphorylated amino acid binding
What is protein phosphorylated amino acid binding?
It is a molecular function (GO:0045309) defined as binding to a phosphorylated amino acid residue within a protein [QuickGO definition].
What genes are involved in protein phosphorylated amino acid binding?
Genes such as RRAGA, RRAGB, CRK, SMN1, and PTEN encode proteins that exhibit this activity [1,5,6].
How does protein phosphorylated amino acid binding affect mTORC1 signaling?
Rag GTPases bind phosphorylated amino acids to recruit mTORC1 to the lysosome, activating it in response to amino acids [1,2].
What diseases are associated with defects in protein phosphorylated amino acid binding?
Cancer, spinal muscular atrophy, and metabolic disorders have been linked to dysregulation of this function.
What methods are used to study protein phosphorylated amino acid binding?
Common methods include Ribo-seq, phosphoproteomics, co-immunoprecipitation, and fluorescence microscopy [3,4].
Can CRISPR be used to study protein phosphorylated amino acid binding?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression are powerful tools for dissecting this function.
What is the role of c-Crk in protein phosphorylated amino acid binding?
c-Crk contains an SH2 domain that binds to tyrosine-phosphorylated proteins, mediating signal transduction.
How is protein phosphorylated amino acid binding regulated?
It is regulated by the phosphorylation state of target proteins, which is controlled by kinases and phosphatases.
What is the integrated stress response?
A cellular pathway that modulates translation initiation in response to stress, involving GCN2 binding to phosphorylated eIF2α.
How can EDITGENE help with my research on protein phosphorylated amino acid binding?
EDITGENE offers CRISPR knockout, point mutation, knock-in, overexpression, library screening, and bioinformatics services to support your studies.
Conclusion
Protein phosphorylated amino acid binding (GO:0045309) is a fundamental molecular function that underpins cellular signal transduction. Its role in pathways such as mTORC1 signaling and the integrated stress response highlights its importance in health and disease. By leveraging CRISPR-based models and advanced methodologies, researchers can continue to unravel the complexities of this function and identify new therapeutic targets.
References
- 1. Sancak Y et al.. 2008. The Rag GTPases bind raptor and mediate amino acid signaling to mTORC1.. Science 320(5882):1496-501 PMID: 18497260
- 2. Cui Z et al.. 2023. Structure of the lysosomal mTORC1-TFEB-Rag-Ragulator megacomplex.. Nature 614(7948):572-579 PMID: 36697823
- 3. Harding HP et al.. 2000. Regulated translation initiation controls stress-induced gene expression in mammalian cells.. Mol Cell 6(5):1099-108 PMID: 11106749
- 4. Talaia G et al.. 2024. Lysosomal TBK1 responds to amino acid availability to relieve Rab7-dependent mTORC1 inhibition.. EMBO J 43(18):3948-3967 PMID: 39103493
- 5. Fajardo JE et al.. 1993. A 31-amino-acid N-terminal extension regulates c-Crk binding to tyrosine-phosphorylated proteins.. Mol Cell Biol 13(12):7295-302 PMID: 7504172
- 6. Rademacher S et al.. 2020. A Single Amino Acid Residue Regulates PTEN-Binding and Stability of the Spinal Muscular Atrophy Protein SMN.. Cells 9(11) PMID: 33153033
- 7. Sattlegger E et al.. 2004. YIH1 is an actin-binding protein that inhibits protein kinase GCN2 and impairs general amino acid control when overexpressed.. J Biol Chem 279(29):29952-62 PMID: 15126500
