GO:0034589 hydroxyproline transport: Amino Acid Transport Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0034589 (hydroxyproline transport) describes the directed movement of hydroxyproline into, out of, or within a cell, or between cells, via transporters or pores.
• Hydroxyproline is a non-standard amino acid generated mainly by post-translational hydroxylation of proline residues in collagen and other proteins.
• Transport of hydroxyproline is mediated by amino acid transporters such as ASCT1 (SLC1A4), which exchanges neutral amino acids including proline and hydroxyproline.
• In legume endosymbionts like Sinorhizobium meliloti, a dedicated hydroxyproline transport system supports symbiotic nitrogen fixation.
• Hydroxyproline transport influences collagen stability, iron absorption, and cancer metastasis through metabolic reprogramming.
• Dysregulated hydroxyproline transport and metabolism are linked to aminoacidurias, bone metastasis, and intestinal iron uptake disorders.
Description
Hydroxyproline transport (GO:0034589) is a biological process defined as the directed movement of hydroxyproline into, out of, or within a cell, or between cells, by means of some agent such as a transporter or pore. Hydroxyproline is a non-proteinogenic amino acid primarily formed by hydroxylation of proline residues in collagen, where it contributes to triple-helix stability and fibril assembly. Because hydroxyproline is not incorporated into proteins through standard ribosomal synthesis, its transport across membranes is essential for its distribution, catabolism, and signaling roles in diverse organisms. Researchers study this process to understand collagen turnover, amino acid homeostasis, and inter-organ metabolic communication. The transport of hydroxyproline has been characterized in mammalian kidney mitochondria, where it is taken up by specific carriers, and in the neutral amino-acid exchanger ASCT1, which mediates proline and hydroxyproline flux. In plants and their symbionts, hydroxyproline-rich glycoproteins and dedicated transport systems play roles in cell wall structure and symbiotic interactions. In humans, altered hydroxyproline transport and metabolism are associated with metabolic bone diseases, cancer progression, and intestinal iron absorption. Understanding GO:0034589 therefore bridges basic amino acid transport biology with clinically relevant processes such as metastasis and nutrient uptake.
hydroxyproline transport At A Glance
| GO ID | GO:0034589 |
|---|---|
| GO term | hydroxyproline transport |
| Ontology | biological_process |
| Synonym | 4-hydroxyproline transport; L-hydroxyproline transport |
| Definition | The directed movement of hydroxyproline into, out of or within a cell, or between cells, by means of some agent such as a transporter or pore. |
| Major function | Mediates cellular uptake, efflux, and distribution of hydroxyproline, a key amino acid in collagen metabolism and signaling. |
| Related transporters | ASCT1 (SLC1A4); mitochondrial carriers in kidney; Sinorhizobium meliloti transport system. |
| Physiological contexts | Collagen turnover, intestinal iron absorption, symbiotic nitrogen fixation, cancer metabolism. |
| Associated diseases | Aminoaciduria, breast cancer bone metastasis, iron-related disorders. |
What Is GO:0034589?
In simple terms, GO:0034589 describes how the amino acid hydroxyproline is moved across cellular membranes. According to the QuickGO definition, it is the directed movement of hydroxyproline into, out of or within a cell, or between cells, by means of some agent such as a transporter or pore. This process includes uptake from the extracellular environment, release from cells, and redistribution between intracellular compartments. It is mediated by membrane proteins that recognize hydroxyproline as a substrate, often in competition or exchange with other neutral amino acids such as proline. The process is distinct from hydroxyproline biosynthesis or catabolism, focusing specifically on its transport.
Why Is hydroxyproline transport Important in Cell Biology?
Hydroxyproline transport is important because it controls the availability of a unique amino acid that serves as a biomarker of collagen degradation and a regulator of cellular metabolism. In mammals, hydroxyproline released from collagen breakdown must be transported into cells for catabolism or excretion, and defects in this process can lead to metabolic imbalances. In cancer, hydroxyproline metabolism in the bone microenvironment promotes breast cancer metastasis, highlighting the clinical relevance of transport and subsequent metabolic steps. In the intestine, hydroxyproline-rich peptides stimulate iron absorption by upregulating iron transport proteins, linking hydroxyproline transport to nutritional iron homeostasis. In plants and rhizobia, hydroxyproline transport supports symbiotic interactions and cell wall dynamics. Thus, studying GO:0034589 provides insights into amino acid trafficking, inter-organ communication, and disease mechanisms.
• Hydroxyproline is a major component of collagen, and its transport is required for collagen turnover and recycling.
• Transporters such as ASCT1 mediate hydroxyproline flux and influence neurotransmitter and amino acid balance.
• Mitochondrial hydroxyproline transport in kidney is essential for hydroxyproline catabolism and energy metabolism.
• In Sinorhizobium meliloti, a dedicated hydroxyproline transport system is required for efficient legume nodulation.
• Hydroxyproline transport and metabolism in the bone microenvironment promote breast cancer metastasis.
• Gum Arabic-derived hydroxyproline-rich peptides enhance intestinal nonheme iron absorption via HIF2α-dependent upregulation of iron transport proteins.
• Aminoacidurias can result from defective renal transport of amino acids including hydroxyproline.
• Hydroxyproline transport is a potential target for modulating collagen-related pathologies and cancer progression.
• Understanding hydroxyproline transport aids in interpreting biomarkers of bone and collagen metabolism.
• The process is conserved across kingdoms, from bacteria to plants to mammals, underscoring its fundamental role.
What Happens During hydroxyproline transport?
Substrate recognition and binding
In simple terms: The transporter first recognizes and binds hydroxyproline.
Transport of hydroxyproline begins with its recognition by a membrane transporter. The neutral amino-acid exchanger ASCT1 (SLC1A4) binds hydroxyproline and other neutral amino acids such as proline, alanine, serine, and cysteine, and mediates their exchange across the plasma membrane. In rat kidney mitochondria, a specific transport system recognizes hydroxyproline for uptake into the organelle. In the legume endosymbiont Sinorhizobium meliloti, a dedicated transport system is required for hydroxyproline utilization, indicating specific substrate recognition.
Translocation across the membrane
In simple terms: The transporter moves hydroxyproline across the membrane.
After binding, the transporter undergoes conformational changes to translocate hydroxyproline across the lipid bilayer. ASCT1 functions as an exchanger, coupling the movement of hydroxyproline to the counter-transport of another neutral amino acid, thereby maintaining substrate gradients. In mitochondria, hydroxyproline is transported into the matrix, likely via a carrier-mediated process that is energy-dependent or linked to proton gradients. In bacteria, the transport system enables hydroxyproline uptake from the environment, supporting its use as a carbon and nitrogen source.
Intracellular distribution and metabolism
In simple terms: Once inside, hydroxyproline is distributed to where it is needed or broken down.
Following transport, hydroxyproline can be metabolized or incorporated into specialized structures. In mammals, hydroxyproline is catabolized primarily in mitochondria, where it is converted to glyoxylate and pyruvate, contributing to energy production. In plants, hydroxyproline residues in proteins are substrates for O-arabinosylation, affecting cell wall glycoprotein function. In cancer cells, hydroxyproline metabolism in the bone microenvironment supports metastatic growth, suggesting that transport fuels metabolic pathways.
Regulation of transport activity
In simple terms: The activity of hydroxyproline transporters can be turned up or down.
Transport activity is regulated at multiple levels. In the intestine, hydroxyproline-rich peptides stimulate iron absorption by upregulating iron transport proteins via HIF2α, indirectly linking hydroxyproline availability to transport regulation. In symbiotic bacteria, expression of the hydroxyproline transport system is likely induced by the presence of hydroxyproline or plant signals. In mammals, amino acid transporters like ASCT1 are subject to regulation by substrate availability and cellular demand. Mitochondrial hydroxyproline transport may be modulated by metabolic state.
Physiological outcomes
In simple terms: Hydroxyproline transport affects many body functions.
The transport of hydroxyproline has diverse physiological consequences. It supports collagen synthesis and turnover by providing hydroxyproline for degradation and recycling. It contributes to renal amino acid homeostasis, and defects can lead to aminoaciduria. In the gut, it enhances iron absorption, impacting systemic iron status. In cancer, it promotes metastasis in the bone microenvironment. In agriculture, it supports symbiotic nitrogen fixation in legumes.
Key Genes Involved in GO:0034589 hydroxyproline transport
The following genes and proteins are directly or indirectly involved in hydroxyproline transport and its associated pathways.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SLC1A4 (ASCT1) | Neutral amino-acid exchanger that transports proline and hydroxyproline | Studying substrate specificity and transport kinetics in vitro |
| SLC1A5 (ASCT2) | Neutral amino-acid transporter; may transport hydroxyproline | Potential alternative transporter; less characterized for hydroxyproline |
| PRODH2 | Proline dehydrogenase involved in hydroxyproline metabolism | Target for cancer metastasis studies in bone |
| SLC6A20 | Proline transporter; may recognize hydroxyproline | Investigating substrate promiscuity in amino acid transport |
| SLC36A1 | Proton-coupled amino acid transporter; potential hydroxyproline carrier | Studying intestinal absorption of hydroxyproline |
| SLC38A2 | Sodium-coupled neutral amino acid transporter; may transport hydroxyproline | Exploring broad-specificity transporters |
| SLC7A5 | L-type amino acid transporter; potential hydroxyproline transport | Cancer metabolism research |
| SLC3A2 | Heavy chain of amino acid transporters; partners with SLC7A5 | Studying heterodimeric transporter function |
| P4HA1 | Prolyl 4-hydroxylase; generates hydroxyproline in collagen | Collagen biosynthesis and stability studies |
| P4HA2 | Prolyl 4-hydroxylase; generates hydroxyproline in collagen | Cancer and fibrosis research |
| P4HB | Protein disulfide isomerase; supports prolyl hydroxylation | Collagen folding and transport studies |
| HIF2α (EPAS1) | Transcription factor upregulating iron transport proteins in response to hydroxyproline-rich peptides | Iron absorption and hypoxia research |
| DMT1 (SLC11A2) | Iron transporter upregulated by hydroxyproline-rich peptides | Intestinal iron uptake studies |
| Ferroportin (SLC40A1) | Iron exporter; may be affected by hydroxyproline-rich peptides | Iron homeostasis research |
| Sinorhizobium meliloti transport system | Dedicated hydroxyproline transport system in legume endosymbiont | Symbiotic nitrogen fixation studies |
| Plant O-arabinosyltransferases | Enzymes that modify hydroxyproline residues in glycoproteins | Plant cell wall and glycoprotein research |
| Mitochondrial hydroxyproline carrier | Unidentified transporter in rat kidney mitochondria | Mitochondrial amino acid transport studies |
| Collagen prolyl hydroxylases | Enzymes that produce hydroxyproline in collagen | Collagen-related disease models |
How Is hydroxyproline transport Regulated?
Hydroxyproline transport is regulated by substrate availability, cellular metabolic demand, and signaling pathways. In the intestine, hydroxyproline-rich peptides stimulate iron absorption by upregulating iron transport proteins via HIF2α-dependent mechanisms, indicating that hydroxyproline availability can influence transport regulation. In bacteria, expression of the hydroxyproline transport system is likely induced by the presence of hydroxyproline or plant-derived signals during symbiosis. In mammals, the activity of amino acid transporters such as ASCT1 is modulated by substrate concentrations and cellular needs. Mitochondrial hydroxyproline transport may be regulated by metabolic state and energy demands. Additionally, hydroxyproline metabolism in the bone microenvironment can promote cancer metastasis, suggesting that transport is part of a regulated metabolic network.
hydroxyproline transport and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| PRODH2 | Breast cancer bone metastasis | Knockout of PRODH2 in breast cancer cell lines; bone metastasis mouse models |
| SLC1A4 (ASCT1) | Aminoaciduria; neurological disorders | Knockout mice; patient-derived cells; transport assays |
| HIF2α (EPAS1) | Iron absorption disorders | Intestinal epithelial cell lines; HIF2α knockout mice |
| P4HA1/P4HA2 | Collagen-related diseases, fibrosis | Knockout in fibroblasts; collagen stability assays |
| Sinorhizobium meliloti transport system | Symbiotic nitrogen fixation | Bacterial knockout; plant infection models |
Hydroxyproline transport in cancer metastasis
PRODH2-mediated hydroxyproline metabolism in the bone microenvironment promotes breast cancer metastasis, indicating that hydroxyproline transport and subsequent catabolism support metastatic growth. This suggests that targeting hydroxyproline transport could be a therapeutic strategy in bone-metastatic breast cancer.
Aminoacidurias and renal transport defects
Defects in renal amino acid transport can lead to aminoacidurias, including increased excretion of hydroxyproline. These conditions highlight the importance of hydroxyproline transport in kidney function and amino acid homeostasis.
Hydroxyproline and iron absorption disorders
Gum Arabic-derived hydroxyproline-rich peptides stimulate intestinal nonheme iron absorption via HIF2α-dependent upregulation of iron transport proteins. This links hydroxyproline transport to nutritional iron homeostasis and potential therapies for iron deficiency.
Collagen-related pathologies
Hydroxyproline is critical for collagen stability, and its transport affects collagen turnover. Dysregulation of hydroxyproline transport may contribute to fibrotic diseases and connective tissue disorders, though direct evidence is still emerging.
From hydroxyproline transport-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of SLC1A4 affect hydroxyproline transport? | SLC1A4 knockout cell lines (e.g., HEK293) |
| Does PRODH2-mediated hydroxyproline metabolism promote metastasis? | PRODH2 knockout breast cancer cells in bone metastasis mouse models |
| How do point mutations in SLC1A4 alter substrate specificity? | Point-mutation knock-in cell lines expressing mutant SLC1A4 |
| Can tagged SLC1A4 reveal subcellular localization? | Knock-in of fluorescent or epitope tags at the endogenous SLC1A4 locus |
| Does overexpression of ASCT1 increase hydroxyproline uptake? | Overexpression of SLC1A4 in mammalian cells |
| What is the role of hydroxyproline transport in iron absorption? | Intestinal epithelial cells treated with hydroxyproline-rich peptides; HIF2α knockout |
How to Study the hydroxyproline transport Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Radiolabeled uptake assay | Transport rate and kinetics | Characterizing ASCT1-mediated hydroxyproline transport |
| Mitochondrial swelling assay | Mitochondrial hydroxyproline uptake | Studying kidney mitochondrial transport |
| CRISPR knockout | Gene requirement for transport | Validating SLC1A4 as a hydroxyproline transporter |
| Metabolomics (LC-MS) | Hydroxyproline and metabolite levels | Cancer metabolism and iron absorption studies |
| Fluorescence microscopy | Subcellular localization of transporters | Tagged SLC1A4 knock-in cells |
| qPCR/Western blot | Expression of transport-related genes | Regulation by hydroxyproline-rich peptides |
| Bacterial genetics | Hydroxyproline utilization | Sinorhizobium meliloti transport system |
| Plant glycoprotein analysis | O-arabinosylation of hydroxyproline | Plant cell wall studies |
Transport assays
Radiolabeled or fluorescent hydroxyproline uptake assays in cell lines or isolated mitochondria can measure transport kinetics and substrate specificity. These assays are used to characterize transporters like ASCT1 and mitochondrial carriers.
Genetic knockout and knockdown
CRISPR-Cas9 knockout or RNAi knockdown of candidate transporters (e.g., SLC1A4) followed by transport assays can establish causality. Such models help determine whether a gene is required for hydroxyproline transport.
Metabolic profiling
Mass spectrometry-based metabolomics can quantify hydroxyproline and its metabolites in cells and tissues, revealing changes in transport and catabolism. This is useful in cancer and iron absorption studies.
Imaging and localization
Fluorescent tagging of transporters or use of fluorescent hydroxyproline analogs can visualize transport dynamics and subcellular localization. Mitochondrial transport can be studied with isolated organelles.
How CRISPR Can Be Used to Study GO:0034589 hydroxyproline transport
Knockout
CRISPR knockout of candidate hydroxyproline transporters such as SLC1A4 can abolish transport activity, providing direct evidence of their role. Knockout models are also used to study the contribution of hydroxyproline transport to cancer metastasis and iron absorption.
Point Mutation
Introducing point mutations in transporter genes (e.g., SLC1A4) can reveal residues critical for substrate recognition and transport. Such models help dissect the molecular basis of hydroxyproline specificity.
Knock-in
Knock-in of epitope or fluorescent tags at endogenous loci allows visualization and purification of transporters without overexpression artifacts. This approach is valuable for studying localization and dynamics of hydroxyproline transporters.
Overexpression
Overexpression of transporters like ASCT1 in cell lines can enhance hydroxyproline uptake and enable detailed kinetic studies. Overexpression models are also used to investigate downstream metabolic effects.
How EDITGENE Supports hydroxyproline transport Research
Researchers studying hydroxyproline transport-related genes often need to determine whether a candidate gene is causally involved in transport, metabolism, or disease. EDITGENE provides comprehensive CRISPR-based services to generate knockout, point-mutation, knock-in, and overexpression cell models, as well as library screening and bioinformatics support, enabling rigorous functional studies of GO:0034589 and its associated genes.
Contact EDITGENE today to design your custom CRISPR model for hydroxyproline transport research.
Frequently Asked Questions About hydroxyproline transport
What is hydroxyproline transport?
Hydroxyproline transport (GO:0034589) is the directed movement of hydroxyproline into, out of, or within a cell, or between cells, by means of a transporter or pore.
What genes are involved in hydroxyproline transport?
Key genes include SLC1A4 (ASCT1), which exchanges proline and hydroxyproline, and mitochondrial carriers in kidney. In bacteria, a dedicated transport system exists in Sinorhizobium meliloti.
How is hydroxyproline transported across cell membranes?
It is transported by membrane proteins such as ASCT1, which functions as a neutral amino-acid exchanger. Mitochondrial uptake occurs via specific carriers.
What is the role of hydroxyproline transport in cancer?
Hydroxyproline metabolism in the bone microenvironment promotes breast cancer metastasis, suggesting that transport fuels metastatic growth.
Is hydroxyproline transport linked to iron absorption?
Yes, hydroxyproline-rich peptides stimulate intestinal iron absorption by upregulating iron transport proteins via HIF2α.
What diseases are associated with defective hydroxyproline transport?
Defects can lead to aminoacidurias, and altered transport is linked to cancer metastasis and iron disorders.
How can I study hydroxyproline transport in the lab?
Use radiolabeled uptake assays, CRISPR knockout of candidate transporters, and metabolomics to measure transport and metabolism.
What model systems are used for hydroxyproline transport research?
Common models include mammalian cell lines (e.g., HEK293), isolated mitochondria, and bacterial systems like Sinorhizobium meliloti.
Does hydroxyproline transport occur in plants?
Yes, plants transport hydroxyproline for cell wall glycoprotein modification, and symbiotic bacteria have dedicated transport systems.
What are the synonyms for GO:0034589?
The synonyms are 4-hydroxyproline transport and L-hydroxyproline transport.
Conclusion
Hydroxyproline transport (GO:0034589) is a fundamental biological process that governs the movement of a unique amino acid critical for collagen metabolism, cellular signaling, and inter-organ communication. Its study spans from bacterial symbiosis to human cancer and iron homeostasis, with key transporters like ASCT1 and mitochondrial carriers playing central roles. Understanding the regulation and function of hydroxyproline transport offers insights into disease mechanisms and potential therapeutic targets. EDITGENE provides the CRISPR tools needed to dissect this process with precision.
References
- 1. Gong H et al.. 2025. PRODH2-Mediated Metabolism in the Bone Microenvironment Promotes Breast Cancer Metastasis.. Cancer Res 85(21):4198-4211 PMID: 40749014
- 2. Orieshyna A et al.. 2023. Proton Transport Across Collagen Fibrils and Scaffolds: The Role of Hydroxyproline.. Biomacromolecules 24(11):4653-4662 PMID: 37656903
- 3. Petersen BL et al.. 2021. Plant Protein O-Arabinosylation.. Front Plant Sci 12:645219 PMID: 33815452
- 4. Maclean AM et al.. 2009. Identification of a hydroxyproline transport system in the legume endosymbiont Sinorhizobium meliloti.. Mol Plant Microbe Interact 22(9):1116-27 PMID: 19656046
- 5. EFRON ML. 1965. AMINOACIDURIA.. N Engl J Med 272:1107-13 CONCL PMID: 14281555
- 6. Pinilla-Tenas J et al.. 2003. Transport of proline and hydroxyproline by the neutral amino-acid exchanger ASCT1.. J Membr Biol 195(1):27-32 PMID: 14502423
- 7. Li S et al.. 2024. Gum Arabic-Derived Hydroxyproline-Rich Peptides Stimulate Intestinal Nonheme Iron Absorption via HIF2α-Dependent Upregulation of Iron Transport Proteins.. J Agric Food Chem 72(7):3622-3632 PMID: 38347764
- 8. Atlante A et al.. 1994. Spectroscopic study of hydroxyproline transport in rat kidney mitochondria.. Biochem Biophys Res Commun 202(1):58-64 PMID: 8037764
