GO:1904983 glycine import into mitochondrion: Transport Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1904983 (glycine import into mitochondrion) is the biological process that moves glycine from the cytosol into the mitochondrial matrix.
• Mitochondrial glycine import supplies the one-carbon and heme biosynthetic pathways, linking glycine availability to nucleotide synthesis, redox balance and energy metabolism.
• The process is experimentally tractable using isolated-organelle import assays, precursor-protein import systems and mitochondrial targeting-signal studies.
• Glycine-rich and GxxxG motifs in translocase components influence mitochondrial protein import and can be used as mechanistic handles.
• Dysregulated mitochondrial glycine handling is implicated in cancer cell proliferation and in disorders of heme biosynthesis and iron metabolism.
• CRISPR knockout, point-mutation, knock-in and overexpression models allow causal testing of genes proposed to mediate mitochondrial glycine import.
Description
GO:1904983, glycine import into mitochondrion, is a biological process defined as the transport of glycine from the cytosol into the mitochondrial matrix. Glycine is the smallest amino acid and serves as a precursor for heme, glutathione, purines and one-carbon units, so its delivery into mitochondria is a metabolic bottleneck for several biosynthetic routes. The term is therefore of interest to researchers studying mitochondrial metabolism, amino acid compartmentalization and organelle biogenesis. Experimental work on mitochondrial import has historically used precursor proteins and model peptides to define how cytosolic cargo is recognized and translocated into the organelle. Those studies established the conceptual framework in which small-molecule and amino-acid import steps, including glycine import, are now investigated. Because glycine import into the mitochondrial matrix is required for mitochondrial one-carbon metabolism and heme synthesis, perturbations in this process can alter proliferation, redox homeostasis and energy production. Understanding GO:1904983 therefore connects basic organelle transport biology to cancer metabolism and inherited metabolic disease.
glycine import into mitochondrion At A Glance
| GO ID | GO:1904983 |
|---|---|
| GO term | glycine import into mitochondrion |
| Ontology | biological_process |
| Synonym | transmembrane glycine transport from cytosol to mitochondrion |
| Definition | The process in which glycine is transported from the cytosol into the mitochondrial matrix. |
| Major function | Delivery of cytosolic glycine to the mitochondrial matrix for one-carbon metabolism, heme biosynthesis and related biosynthetic pathways |
| Directionality | Cytosol to mitochondrial matrix |
| Compartment | Mitochondrial matrix |
| Related processes | Mitochondrial protein import, heme biosynthesis, one-carbon metabolism |
What Is GO:1904983?
In plain terms, GO:1904983 describes the step in which a molecule of glycine leaves the cytosol and enters the mitochondrial matrix. The QuickGO definition states that it is the process in which glycine is transported from the cytosol into the mitochondrial matrix. It is a biological_process term, not a molecular-function or cellular-component term, and its synonym is transmembrane glycine transport from cytosol to mitochondrion. The term covers the net vectorial movement of glycine across the mitochondrial boundary into the matrix compartment, where glycine can be used by mitochondrial enzymes such as those in one-carbon and heme biosynthesis.
Why Is glycine import into mitochondrion Important in Cell Biology?
Glycine import into the mitochondrion matters because mitochondrial glycine is a substrate for enzymes that generate one-carbon units and heme, and these pathways influence nucleotide synthesis, redox defense and cellular energy status. When glycine cannot reach the matrix efficiently, mitochondrial one-carbon metabolism and heme production can be compromised, with downstream effects on proliferation and iron handling. Because the process sits at the interface of amino acid metabolism and organelle biology, it is a useful node for studying metabolic compartmentalization and for identifying therapeutic vulnerabilities in cancer and metabolic disease.
• Supplies glycine to mitochondrial one-carbon metabolism, supporting nucleotide biosynthesis and methylation reactions.
• Provides glycine for heme biosynthesis, connecting the process to iron metabolism and cellular energy production.
• Influences cancer cell proliferation, as mitochondrial serine hydroxymethyltransferase and glycine handling are required for tumor cell growth.
• Represents a compartmentalization step that determines whether cytosolic glycine can be used by mitochondrial enzymes.
• Can be studied with established mitochondrial import assays and precursor-protein systems.
• Involves targeting-signal and motif features that are experimentally dissectable, such as glycine-rich and GxxxG motifs.
• Links to plant and mammalian mitochondrial import biology, enabling comparative studies.
• Provides a rationale for CRISPR-based causal testing of candidate transport and metabolic genes.
What Happens During glycine import into mitochondrion?
Recognition of glycine at the mitochondrial boundary
In simple terms: The mitochondrion must first distinguish glycine from other small molecules before letting it in.
Glycine import into the mitochondrion begins with the availability of cytosolic glycine and its interaction with the mitochondrial boundary. Studies of mitochondrial import using model extension peptides containing glycine, proline and serine residues showed that glycine-rich sequences influence the import of mitochondrial enzyme precursors, indicating that glycine content is relevant to mitochondrial targeting and import. This provides a conceptual basis for understanding how glycine itself is handled at the organelle interface.
Translocation across the mitochondrial membranes
In simple terms: Glycine is moved across the mitochondrial membrane system into the interior compartment.
The defining event of GO:1904983 is transmembrane transport of glycine from the cytosol into the mitochondrial matrix. Mitochondrial import systems have been characterized using in vitro assays that simultaneously monitor import of precursor proteins into mitochondria and chloroplasts, demonstrating that the mitochondrial boundary is a selective translocation barrier. Soybean mitochondrial import studies further showed that precursor import into mitochondria is developmentally regulated, indicating that the import capacity of the organelle changes with physiological state.
Delivery into the mitochondrial matrix
In simple terms: Once inside, glycine reaches the matrix where mitochondrial enzymes can use it.
After crossing the mitochondrial boundary, glycine is delivered into the mitochondrial matrix. The matrix is the site of mitochondrial one-carbon metabolism and heme biosynthesis, both of which consume glycine. RNA-mediated inhibition of mitochondrial SHMT2 impairs cancer cell proliferation, showing that matrix-localized glycine-dependent metabolism is functionally important for cell growth. This links the endpoint of glycine import to a defined matrix biosynthetic function.
Coupling to heme and iron metabolism
In simple terms: Glycine delivered to the matrix is used to build heme, which is needed for oxygen transport and energy production.
Glycine import into the mitochondrion is coupled to heme biosynthesis, because glycine is a substrate for the first committed step of heme synthesis in the matrix. An update on heme biosynthesis, tissue-specific regulation, heme transport and its relation to iron metabolism and cellular energy highlights the integration of mitochondrial glycine use with iron handling and energy metabolism. This makes GO:1904983 relevant to disorders in which heme production or iron distribution is perturbed.
Regulation by developmental and physiological state
In simple terms: How much glycine gets into mitochondria can change depending on the cell's condition.
Mitochondrial import capacity is not static. Import of precursor proteins into mitochondria from soybean tissues changes during development, indicating that mitochondrial import is regulated by developmental and physiological cues. A novel in vitro system for simultaneous import of precursor proteins into mitochondria and chloroplasts further enabled comparative analysis of import under different conditions. These observations support the view that glycine import into the mitochondrion is a regulated process rather than a constitutive leak.
Key Genes Involved in GO:1904983 glycine import into mitochondrion
The following genes and proteins are experimentally linked to mitochondrial import, glycine-dependent mitochondrial metabolism, or heme biosynthesis, and are therefore relevant to research on GO:1904983.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SHMT2 | Mitochondrial serine hydroxymethyltransferase that interconverts serine and glycine in the matrix | RNA-mediated inhibition impairs cancer cell proliferation, linking matrix glycine metabolism to growth |
| ALAS1 | First enzyme of heme biosynthesis, which uses glycine in the mitochondrial matrix | Connects glycine import to heme biosynthesis and iron metabolism |
| ALAS2 | Erythroid-specific heme biosynthesis enzyme using glycine | Relevant to tissue-specific regulation of heme synthesis and glycine demand |
| FECH | Final enzyme of heme biosynthesis in mitochondria | Links mitochondrial glycine use to heme maturation and iron handling |
| ABCB6 | Mitochondrial transporter implicated in heme and porphyrin transport | Relevant to mitochondrial transport and heme-related metabolism |
| ABCB7 | Mitochondrial transporter involved in iron-sulfur cluster and heme-related pathways | Connects mitochondrial transport to iron metabolism and energy |
| TIM23 | Core subunit of the mitochondrial inner membrane translocase | GxxxG motifs hold the TIM23 complex together, informing import mechanism studies |
| TIM17 | Component of the TIM23 translocase complex | Relevant to inner membrane translocation mechanisms |
| TOM20 | Outer membrane receptor for mitochondrial precursor proteins | Model receptor for studying mitochondrial import recognition |
| TOM40 | Outer membrane channel of the mitochondrial import machinery | Central to translocation across the outer membrane |
| AOX | Alternative oxidase, a mitochondrial protein used as an import model | Signals required for import and processing have been defined using this protein |
| CYP11A1 | Mammalian cytochrome P450 (scc) precursor used in import studies | Demonstrates import of mammalian precursors into plant mitochondria |
| MPP | Mitochondrial processing peptidase that cleaves imported precursors | Relevant to processing steps after import |
| HSP70 | Mitochondrial chaperone assisting imported proteins | Supports folding and import competence |
| SHMT1 | Cytosolic serine hydroxymethyltransferase | Provides a compartmental counterpart to mitochondrial SHMT2 |
| MTHFD2 | Mitochondrial one-carbon enzyme | Downstream consumer of matrix one-carbon units derived from glycine |
| GCSH | Glycine cleavage system H protein | Mitochondrial glycine cleavage component relevant to glycine utilization |
| GLDC | Glycine decarboxylase | Mitochondrial enzyme that uses glycine in the matrix |
How Is glycine import into mitochondrion Regulated?
Mitochondrial import capacity is regulated by developmental and physiological state, as shown by changes in precursor protein import into mitochondria from soybean tissues during development. Comparative in vitro import systems have been used to monitor import into mitochondria and chloroplasts simultaneously, enabling assessment of how import is modulated under different conditions. In addition, glycine-rich and GxxxG motifs within translocase components such as TIM23 influence the stability and function of the import machinery, providing a structural layer of regulation. At the metabolic level, mitochondrial glycine utilization is tied to one-carbon metabolism and heme biosynthesis, so flux through these pathways can feed back on the demand for glycine import.
glycine import into mitochondrion and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SHMT2 | Cancer cell proliferation and one-carbon metabolism | SHMT2 knockout and overexpression in cancer cell lines |
| ALAS1 | Heme biosynthesis and iron metabolism disorders | ALAS1 point-mutation and knockout models in hepatocyte-like cells |
| ALAS2 | Erythroid heme biosynthesis | ALAS2 knock-in and knockout in erythroid cells |
| FECH | Heme maturation and iron handling | FECH knockout and tagged knock-in for localization studies |
| TIM23 | Mitochondrial import machinery dysfunction | TIM23 point-mutation models targeting GxxxG motifs |
Cancer metabolism and proliferation
Mitochondrial glycine metabolism supports cancer cell proliferation. RNA-mediated inhibition of mitochondrial SHMT2 impairs cancer cell proliferation, demonstrating that matrix-localized glycine-dependent one-carbon metabolism is required for tumor cell growth. Because glycine import into the mitochondrion supplies substrate to SHMT2 and related enzymes, defects or inhibition of this import step could reduce proliferative capacity.
Disorders of heme biosynthesis and iron metabolism
Glycine delivered to the mitochondrial matrix is used for heme biosynthesis, and heme production is tightly linked to iron metabolism and cellular energy. An update on heme biosynthesis, tissue-specific regulation, heme transport and its relation to iron metabolism highlights how perturbations in these pathways can affect multiple tissues. Consequently, altered glycine import into mitochondria may contribute to phenotypes in which heme synthesis or iron distribution is disturbed.
Mitochondrial import defects
The mitochondrial import machinery is essential for organelle biogenesis, and its components are subject to structural constraints. GxxxG motifs hold the TIM23 complex together, and disruption of such motifs can affect import function. Studies of precursor import into plant and mammalian mitochondria have shown that import is developmentally regulated and can be modeled in vitro, providing a framework for understanding disease-relevant import defects.
From glycine import into mitochondrion-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is a candidate gene required for glycine import into mitochondria? | CRISPR knockout in a mitochondrial-import-competent cell line |
| Does a specific residue control import activity? | Point-mutation knock-in of the candidate residue |
| Where does the candidate protein localize? | Tagged knock-in with a mitochondrial reporter |
| Does increased expression enhance glycine-dependent metabolism? | Overexpression of the candidate gene |
| Does loss of the gene alter proliferation? | SHMT2 knockout and proliferation assays |
| Does the gene affect heme biosynthesis? | ALAS1 or FECH knockout with heme measurements |
How to Study the glycine import into mitochondrion Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Isolated mitochondrial import assay | Uptake of substrates or precursors into mitochondria | Direct functional test of glycine import |
| Model extension peptide assay | Effect of glycine-rich sequences on import | Dissecting import signals |
| Precursor protein import and processing assay | Import and cleavage of mitochondrial precursors | Defining import signals |
| Cross-species import assay | Conservation of import mechanisms | Comparing mammalian and plant mitochondria |
| RNA-mediated inhibition | Loss-of-function effect on proliferation | Testing SHMT2 dependence |
| Heme and iron measurements | Heme biosynthesis and iron handling | Linking glycine import to heme metabolism |
| Developmental import profiling | Changes in import capacity over time | Assessing regulation of import |
| Simultaneous organelle import | Relative import into mitochondria and chloroplasts | Comparative organelle transport studies |
Isolated mitochondrial import assays
In vitro import assays using isolated mitochondria allow direct measurement of precursor or substrate uptake. A novel in vitro system for simultaneous import of precursor proteins into mitochondria and chloroplasts enables comparative analysis of import into two organelles. Soybean mitochondrial import studies demonstrated that import can be monitored across developmental stages.
Model peptide and precursor protein studies
Model extension peptides containing glycine, proline and serine residues have been used to study the import of mitochondrial enzyme precursors, providing a way to dissect how glycine-rich sequences affect import. Signals required for the import and processing of the alternative oxidase into mitochondria have also been defined, offering a template for import-signal analysis.
Cross-species import systems
Import of the mammalian cytochrome P450 (scc) precursor into plant mitochondria demonstrated that mitochondrial import mechanisms can be studied across species. Such systems help distinguish conserved import features from species-specific ones and can be adapted to study glycine-related transport.
Genetic and metabolic perturbation
RNA-mediated inhibition of mitochondrial SHMT2 impairs cancer cell proliferation, illustrating how genetic perturbation can link matrix glycine metabolism to phenotype. Updates on heme biosynthesis and iron metabolism provide the metabolic context for interpreting changes in glycine-dependent mitochondrial pathways.
How CRISPR Can Be Used to Study GO:1904983 glycine import into mitochondrion
Knockout
CRISPR knockout can remove candidate genes such as SHMT2 or ALAS1 to test whether they are required for glycine-dependent mitochondrial metabolism and proliferation. Knockout of SHMT2 impairs cancer cell proliferation, providing a phenotype against which glycine import models can be benchmarked.
Point Mutation
Point-mutation models can target structural motifs such as the GxxxG motifs that hold the TIM23 complex together, allowing residue-level testing of import machinery function. Such models help distinguish catalytic or structural residues from bystander sequences.
Knock-in
Knock-in of tags or reporters enables localization and interaction studies of proteins involved in mitochondrial glycine handling and heme biosynthesis. Tagged knock-in of ALAS1 or FECH can be used to monitor mitochondrial localization and pathway flux.
Overexpression
Overexpression of candidate genes can test whether increased dosage enhances glycine-dependent mitochondrial metabolism or proliferation. Overexpression models complement loss-of-function studies by revealing sufficiency relationships.
How EDITGENE Supports glycine import into mitochondrion Research
Researchers studying glycine import into mitochondrion-related genes often need to determine whether a candidate gene is causally involved in transport, matrix metabolism or heme biosynthesis, rather than merely correlated with a phenotype. CRISPR-based models provide the controlled genetic perturbations required to move from association to causation, and the experimental frameworks for mitochondrial import and glycine-dependent metabolism are well established.
Contact EDITGENE today to design your custom CRISPR model for glycine import into mitochondrion research.
Frequently Asked Questions About glycine import into mitochondrion
What is GO:1904983 glycine import into mitochondrion?
GO:1904983 is a biological process term describing the transport of glycine from the cytosol into the mitochondrial matrix.
What genes are involved in glycine import into mitochondrion?
Genes linked to this process include SHMT2, ALAS1, ALAS2, FECH and mitochondrial translocase components such as TIM23.
Why is glycine import into mitochondria important for cancer?
Mitochondrial glycine metabolism supports one-carbon metabolism, and inhibition of mitochondrial SHMT2 impairs cancer cell proliferation.
How is glycine used inside mitochondria?
Glycine is used in mitochondrial one-carbon metabolism and heme biosynthesis, linking it to nucleotide synthesis, iron metabolism and energy production.
What experimental methods study mitochondrial glycine import?
Isolated mitochondrial import assays, model extension peptide assays, precursor protein import assays and cross-species import systems are used.
Is mitochondrial import regulated during development?
Yes, import of precursor proteins into mitochondria from soybean tissues changes during development, indicating developmental regulation.
What is the synonym for GO:1904983?
The synonym is transmembrane glycine transport from cytosol to mitochondrion.
Which CRISPR model is best for studying glycine import genes?
Knockout is used for loss-of-function tests, point mutation for residue-level questions, knock-in for localization and overexpression for sufficiency studies.
Does glycine import relate to heme biosynthesis?
Yes, glycine delivered to the mitochondrial matrix is a substrate for heme biosynthesis, which is linked to iron metabolism and energy.
Can mitochondrial import be studied across species?
Yes, import of the mammalian cytochrome P450 (scc) precursor into plant mitochondria shows that import mechanisms can be compared across species.
Conclusion
GO:1904983, glycine import into mitochondrion, defines the delivery of cytosolic glycine to the mitochondrial matrix, where it feeds one-carbon metabolism and heme biosynthesis. The process is experimentally accessible through established mitochondrial import assays and can be perturbed with CRISPR knockout, point-mutation, knock-in and overexpression models. Because mitochondrial glycine handling influences proliferation and iron-related metabolism, it is a valuable target for cancer metabolism and metabolic disease research.
References
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- 2. Belot A et al.. 2024. Update on heme biosynthesis, tissue-specific regulation, heme transport, relation to iron metabolism and cellular energy.. Liver Int 44(9):2235-2250 PMID: 38888238
- 3. Park NG et al.. 1989. Effects of model extension peptides containing glycine, proline and serine residues on the import of mitochondrial enzyme precursors into mitochondria.. Pept Res 2(2):178-83 PMID: 2520755
- 4. Murcha MW et al.. 1999. Import of precursor proteins into mitochondria from soybean tissues during development.. FEBS Lett 464(1-2):53-9 PMID: 10611482
- 5. Rudhe C et al.. 2002. A novel in vitro system for simultaneous import of precursor proteins into mitochondria and chloroplasts.. Plant J 30(2):213-20 PMID: 12000457
- 6. Tanudji M et al.. 1999. Signals required for the import and processing of the alternative oxidase into mitochondria.. J Biol Chem 274(3):1286-93 PMID: 9880497
- 7. Demishtein-Zohary K et al.. 2015. GxxxG motifs hold the TIM23 complex together.. FEBS J 282(11):2178-86 PMID: 25765297
- 8. Luzikov VN et al.. 1994. Import of the mammalian cytochrome P450 (scc) precursor into plant mitochondria.. Biochem Biophys Res Commun 199(1):33-6 PMID: 8123031
