The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.
We are interested in where in or outside the cell the gene product carries out its function.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.
Identity verified. The target is human LEPR, the gene encoding the leptin receptor (UniProt P48357; also OB-R and CD295), not LEP, which encodes its leptin ligand. Human LEPR lies at chromosome 1p31.3. Receptor clones isolated from human CD34-positive cells establish its identity as a cytokine receptor and demonstrate human splice variants. Its class-I cytokine-receptor architecture agrees with the supplied UniProt annotations: an extracellular cytokine-receptor region with a WSXWS-related motif, immunoglobulin-like and fibronectin-type-III domains, one membrane-spanning segment in membrane isoforms, and an intracellular signaling tail in the long isoform. The database’s “type 2” designation should not be confused with the separate class II cytokine-receptor family. (collet2024exploringthetherapeutic pages 1-2, bennett1996arolefor pages 1-2, saxton2023structuralinsightsinto pages 1-2, gorska2010leptinreceptors pages 1-2)
LEPR is a cell-surface receptor for the adipocyte-secreted hormone leptin, rather than an enzyme or a general-purpose nutrient transporter. Its principal function is to convert extracellular information about available energy stores into intracellular signaling. The long isoform, LEPRb/Ob-Rb, is the major signaling-competent form. LEPR has no intrinsic kinase activity: leptin-induced receptor assembly and conformational change activate the cytoplasmic kinase JAK2, which associates with the receptor’s membrane-proximal Box1/Box2 region. Short-tailed isoforms retain leptin binding but do not reproduce LEPRb’s full JAK–STAT response. (bodur2025molecularmechanismsand pages 1-2, bodur2025molecularmechanismsand pages 2-3)
How leptin engages the receptor. In a March 2023 cryo-electron-microscopy study, leptin bound the receptor’s second cytokine-homology region at a higher-affinity interface and its immunoglobulin-like region at a second, lower-affinity interface. The resulting assembly is asymmetric: one leptin bridges two receptor chains; the observed, partially open complex can also contain a second leptin bound to one chain. Thus, “one leptin bridges two receptors” describes the activating interface, not necessarily the full complex’s total stoichiometry. Crucially, the purified structural complex used mouse proteins; the authors separately tested signaling with human leptin and full-length human LEPR in cultured cells. The focused ligand-binding map reached 3.8 Å resolution. Structure-guided leptin variants produced partial and pathway-biased responses in experimental systems, but are not established LEPR-directed treatments. Saxton et al., Nature Communications, March 2023. (saxton2023structuralinsightsinto pages 1-2, saxton2023structuralinsightsinto pages 2-3, saxton2023structuralinsightsinto pages 8-9, saxton2023structuralinsightsinto pages 5-7)
Intracellular pathway. Activated JAK2 phosphorylates three especially informative LEPRb tail residues:
The plasma membrane is the principal site of leptin recognition and initiation of LEPRb signaling. Functionally important LEPRb-expressing populations include hypothalamic neurons participating in the arcuate and connected feeding circuits. Leptin signaling can favor POMC–melanocortin activity and restrain orexigenic AgRP/NPY activity; however, neither neuronal population alone accounts for all receptor-dependent control of feeding. Human receptor expression has also been demonstrated in CD34-positive hematopoietic progenitors, although its best-established organismal role concerns central energy sensing. (bodur2025molecularmechanismsand pages 1-2, zhou2013leptinsignalingand pages 4-6, bennett1996arolefor pages 1-2)
Isoform and trafficking distinctions are essential to interpreting any localization annotation:
| LEPR form/state | Principal compartment | Mechanism and functional interpretation | Evidence status |
|---|---|---|---|
| LEPRb (Ob-Rb; long signaling isoform) | Plasma membrane; especially important in specialized hypothalamic neurons | Long cytoplasmic tail recruits JAK2 through Box1/Box2. Activated JAK2 phosphorylates Tyr985 (SOCS3 negative feedback and SHP2–GRB2–ERK), Tyr1077 (STAT5), and Tyr1138 (principally STAT3). Tyr1138–STAT3 is the dominant STAT-dependent pathway in mouse physiology; STAT3 also induces SOCS3, completing feedback inhibition. (bodur2025molecularmechanismsand pages 2-3) | Established receptor-signaling mechanism, supported strongly by biochemical and mouse genetic evidence; human biallelic loss-of-function genetics validates its physiological importance. |
| LEPRa and other short membrane isoforms | Plasma membrane and endosomal trafficking compartments; LEPRa is also expressed in choroid-plexus epithelium | Share the leptin-binding ectodomain but have short cytoplasmic tails containing Box1 without the complete LEPRb signaling apparatus; they can weakly activate JAK2 in overexpression systems but are not equivalent to fully signaling-competent LEPRb. A proposed LEPRa–LRP1 complex mediates leptin uptake/transcytosis at the choroid plexus. (bodur2025molecularmechanismsand pages 2-3, uner2023lrp1mediatesleptin pages 5-8, uner2023lrp1mediatesleptin pages 15-17) | Limited signaling role is established; the transport model is tentative because the 2023 evidence is a bioRxiv preprint using genetically modified mice, rat choroid-plexus cells, and transfected cell lines—not human in-vivo validation. |
| Soluble LEPR (LepRe plus shed ectodomain) | Extracellular fluid and blood plasma | A secreted extracellular-domain isoform produced by alternative splicing, together with proteolytically shed membrane-receptor ectodomain, forms the principal circulating leptin-binding protein. It can sequester leptin acutely and stabilize or transport ligand over longer periods, but it lacks a transmembrane/cytoplasmic signaling apparatus. (bodur2025molecularmechanismsand pages 2-3, gorska2010leptinreceptors pages 1-2) | Established ligand-binding/regulatory form; not a cell-autonomous signaling receptor. |
| Nascent/biosynthetic LEPRb | Endoplasmic reticulum, then secretory pathway en route to the plasma membrane | Newly synthesized LEPRb is folding-prone and subject to SEL1L–HRD1 ER-associated degradation. Defective quality control causes aggregation, ER retention, reduced surface delivery, and weaker leptin signaling; the human obesity-associated C604S receptor is folding-defective. The ER is therefore a biogenesis/quality-control compartment, not the normal site of leptin signal transduction. (mao2024theroleof pages 91-95, mao2024regulationofleptin pages 1-2, qi2024sel1lhrd1erassociateddegradation pages 9-13) | Peer-reviewed 2024 evidence is primarily from mouse POMC-neuron genetics and engineered-cell experiments, with human relevance supported by analysis of the C604S disease variant. |
Table: Comparison of signaling-competent LEPRb, short membrane isoforms, soluble receptor, and the biosynthetic ER pool. The table distinguishes established plasma-membrane signaling from tentative transport functions and intracellular quality control.
The receptor is synthesized and quality-controlled in the endoplasmic reticulum (ER), but ER retention is not its normal site of extracellular-leptin sensing. A September 2024 peer-reviewed study found that disrupting SEL1L–HRD1 ER-associated degradation reduced receptor maturation/surface delivery and leptin responses in experimental systems; POMC-neuron deletion studies were in mice, while experiments also examined the obesity-associated human LEPR C604S variant. This establishes a plausible, experimentally tested link between protein folding, membrane availability and signaling without showing that the same ER defect causes common human obesity. Mao et al., Nature Communications, September 2024. (mao2024regulationofleptin pages 1-2, mao2024theroleof pages 91-95)
A further proposed role for short LEPRa is participation with LRP1 in leptin uptake at the choroid plexus. A July 2023 bioRxiv preprint reports interaction and uptake experiments using mouse models and cultured cells; whether this mechanism makes a quantitatively important contribution to human brain leptin entry remains unproven. The circulating soluble receptor, produced by a secreted isoform and receptor-ectodomain shedding, binds leptin outside cells but cannot initiate signaling through an intracellular tail. Uner et al., bioRxiv, July 2023. (uner2023lrp1mediatesleptin pages 5-8, uner2023lrp1mediatesleptin pages 1-5, bodur2025molecularmechanismsand pages 2-3)
Loss of receptor function is direct human evidence for the pathway. In a deliberately enriched cohort of 300 people with hyperphagia and severe early-onset obesity, sequencing found pathogenic LEPR variants in 8 (about 3%): seven homozygotes and one compound heterozygote. Tested missense variants impaired receptor signaling. Affected individuals showed severe hyperphagia and obesity, delayed puberty associated with hypogonadotropic hypogonadism, and measurable immune abnormalities. Importantly, circulating leptin was generally appropriate for the increased fat mass, so a very high leptin concentration relative to adiposity is not required to diagnose LEPR deficiency. The 3% figure applies to this selected cohort, not the general population. Farooqi et al., New England Journal of Medicine, January 2007. (farooqi2007clinicalandmolecular pages 1-2, farooqi2007clinicalandmolecular pages 5-6)
Precision therapy bypasses, rather than repairs, LEPR. Because receptor-deficient patients cannot reliably respond to leptin replacement, treatment of genetically confirmed biallelic LEPR deficiency uses the downstream MC4R agonist setmelanotide; this differs from replacing the missing hormone with metreleptin in LEP deficiency. In the LEPR phase-3 study, 5 of 11 participants (45%) in the reported one-year analysis achieved at least 10% body-weight loss; the reported mean change in maximum-hunger score was −43.7%. These encouraging results come from a small study, with an open-label treatment period and a hunger measure whose limitations the 2024 review notes. The ClinicalTrials.gov record NCT03287960 lists 15 enrolled overall; that enrollment total should not be substituted for the 11-person published weight-loss denominator. Qamar et al., touchREVIEWS in Endocrinology, October 2024; Collet and Schwitzgebel, Frontiers in Nutrition, December 2024. (qamar2024setmelanotideamelanocortin4 pages 6-7, NCT03287960 chunk 1, collet2024exploringthetherapeutic pages 1-2)
Overall assessment. Human cloning, functional analysis of patient variants and the clinical consequences of biallelic loss establish LEPR as a leptin-responsive signaling receptor essential to the human leptin–melanocortin axis. The strongest molecular model is ligand-dependent LEPRb activation of JAK2–STAT3 with SOCS3 feedback at the cell surface. Precise receptor geometry, contributions of individual tail pathways, ER quality control and short-isoform transport are informed substantially by structural, cultured-cell and animal experiments; these should not be presented as equally established mechanisms in living humans. (bennett1996arolefor pages 1-2, farooqi2007clinicalandmolecular pages 1-2, saxton2023structuralinsightsinto pages 2-3, bodur2025molecularmechanismsand pages 2-3, mao2024regulationofleptin pages 1-2, uner2023lrp1mediatesleptin pages 5-8)
References
(collet2024exploringthetherapeutic pages 1-2): Tinh-Hai Collet and Valerie Schwitzgebel. Exploring the therapeutic potential of precision medicine in rare genetic obesity disorders: a scientific perspective. Frontiers in Nutrition, Dec 2024. URL: https://doi.org/10.3389/fnut.2024.1509994, doi:10.3389/fnut.2024.1509994. This article has 8 citations.
(bennett1996arolefor pages 1-2): Brian D. Bennett, Gregg P. Solar, Jean Q. Yuan, Joanne Mathias, G.Roger Thomas, and William Matthews. A role for leptin and its cognate receptor in hematopoiesis. Current Biology, 6:1170-1180, Sep 1996. URL: https://doi.org/10.1016/s0960-9822(02)70684-2, doi:10.1016/s0960-9822(02)70684-2. This article has 689 citations and is from a highest quality peer-reviewed journal.
(saxton2023structuralinsightsinto pages 1-2): Robert A. Saxton, Nathanael A. Caveney, Maria Dolores Moya-Garzon, Karsten D. Householder, Grayson E. Rodriguez, Kylie A. Burdsall, Jonathan Z. Long, and K. Christopher Garcia. Structural insights into the mechanism of leptin receptor activation. Nature Communications, Mar 2023. URL: https://doi.org/10.1038/s41467-023-37169-6, doi:10.1038/s41467-023-37169-6. This article has 98 citations and is from a highest quality peer-reviewed journal.
(gorska2010leptinreceptors pages 1-2): E. Gorska, K. Popko, A. Stelmaszczyk-Emmel, O. Ciepiela, A. Kucharska, and M. Wasik. Leptin receptors. European Journal of Medical Research, 15:50-54, Nov 2010. URL: https://doi.org/10.1186/2047-783x-15-s2-50, doi:10.1186/2047-783x-15-s2-50. This article has 285 citations and is from a peer-reviewed journal.
(bodur2025molecularmechanismsand pages 1-2): Cagri Bodur, Allison Duensing, and Martin G. Myers. Molecular mechanisms and neural mediators of leptin action. Genes & Development, 39:792-807, May 2025. URL: https://doi.org/10.1101/gad.352550.124, doi:10.1101/gad.352550.124. This article has 23 citations and is from a highest quality peer-reviewed journal.
(bodur2025molecularmechanismsand pages 2-3): Cagri Bodur, Allison Duensing, and Martin G. Myers. Molecular mechanisms and neural mediators of leptin action. Genes & Development, 39:792-807, May 2025. URL: https://doi.org/10.1101/gad.352550.124, doi:10.1101/gad.352550.124. This article has 23 citations and is from a highest quality peer-reviewed journal.
(saxton2023structuralinsightsinto pages 2-3): Robert A. Saxton, Nathanael A. Caveney, Maria Dolores Moya-Garzon, Karsten D. Householder, Grayson E. Rodriguez, Kylie A. Burdsall, Jonathan Z. Long, and K. Christopher Garcia. Structural insights into the mechanism of leptin receptor activation. Nature Communications, Mar 2023. URL: https://doi.org/10.1038/s41467-023-37169-6, doi:10.1038/s41467-023-37169-6. This article has 98 citations and is from a highest quality peer-reviewed journal.
(saxton2023structuralinsightsinto pages 8-9): Robert A. Saxton, Nathanael A. Caveney, Maria Dolores Moya-Garzon, Karsten D. Householder, Grayson E. Rodriguez, Kylie A. Burdsall, Jonathan Z. Long, and K. Christopher Garcia. Structural insights into the mechanism of leptin receptor activation. Nature Communications, Mar 2023. URL: https://doi.org/10.1038/s41467-023-37169-6, doi:10.1038/s41467-023-37169-6. This article has 98 citations and is from a highest quality peer-reviewed journal.
(saxton2023structuralinsightsinto pages 5-7): Robert A. Saxton, Nathanael A. Caveney, Maria Dolores Moya-Garzon, Karsten D. Householder, Grayson E. Rodriguez, Kylie A. Burdsall, Jonathan Z. Long, and K. Christopher Garcia. Structural insights into the mechanism of leptin receptor activation. Nature Communications, Mar 2023. URL: https://doi.org/10.1038/s41467-023-37169-6, doi:10.1038/s41467-023-37169-6. This article has 98 citations and is from a highest quality peer-reviewed journal.
(fruhbeck2006intracellularsignallingpathways pages 3-4): Gema Frühbeck. Intracellular signalling pathways activated by leptin. The Biochemical journal, 393 Pt 1:7-20, Dec 2006. URL: https://doi.org/10.1042/bj20051578, doi:10.1042/bj20051578. This article has 1246 citations.
(zhou2013leptinsignalingand pages 4-6): Yingjiang Zhou and Liangyou Rui. Leptin signaling and leptin resistance. Frontiers of Medicine, 7:207-222, Jun 2013. URL: https://doi.org/10.1007/s11684-013-0263-5, doi:10.1007/s11684-013-0263-5. This article has 614 citations.
(uner2023lrp1mediatesleptin pages 5-8): Aaron Aykut Uner, Won-Mo Yang, Min-Cheol Kang, Kellen Cristina da Cruz Rodrigues, Ahmet Aydogan, Ji A Seo, Natalia F. Mendes, Min-Seon Kim, Fatima Ezzahra Timzoura, Michael J. Holtzman, Maria Lehtinen, Vincent Prevot, and Young-Bum Kim. Lrp1 mediates leptin transport by coupling with the short-form leptin receptor in the choroid plexus. bioRxiv, Jul 2023. URL: https://doi.org/10.1101/2023.07.03.547520, doi:10.1101/2023.07.03.547520. This article has 4 citations.
(uner2023lrp1mediatesleptin pages 15-17): Aaron Aykut Uner, Won-Mo Yang, Min-Cheol Kang, Kellen Cristina da Cruz Rodrigues, Ahmet Aydogan, Ji A Seo, Natalia F. Mendes, Min-Seon Kim, Fatima Ezzahra Timzoura, Michael J. Holtzman, Maria Lehtinen, Vincent Prevot, and Young-Bum Kim. Lrp1 mediates leptin transport by coupling with the short-form leptin receptor in the choroid plexus. bioRxiv, Jul 2023. URL: https://doi.org/10.1101/2023.07.03.547520, doi:10.1101/2023.07.03.547520. This article has 4 citations.
(mao2024theroleof pages 91-95): Hancheng Mao. The role of sel1l-hrd1 endoplasmic reticulum-associated degradation in hypothalamic regulation of metabolism and beyond. Unknown, Jan 2024. URL: https://doi.org/10.7302/22824, doi:10.7302/22824. This article has 0 citations.
(mao2024regulationofleptin pages 1-2): Hancheng Mao, Geun Hyang Kim, Linxiu Pan, and Ling Qi. Regulation of leptin signaling and diet-induced obesity by sel1l-hrd1 er-associated degradation in pomc expressing neurons. Nature Communications, Sep 2024. URL: https://doi.org/10.1038/s41467-024-52743-2, doi:10.1038/s41467-024-52743-2. This article has 26 citations and is from a highest quality peer-reviewed journal.
(qi2024sel1lhrd1erassociateddegradation pages 9-13): Ling Qi, Hancheng Mao, and Geun Hyang Kim. Sel1l-hrd1 er-associated degradation regulates leptin receptor maturation and signaling in pomc neurons in diet-induced obesity. Research Square, Jan 2024. URL: https://doi.org/10.21203/rs.3.rs-3768472/v1, doi:10.21203/rs.3.rs-3768472/v1. This article has 1 citations.
(uner2023lrp1mediatesleptin pages 1-5): Aaron Aykut Uner, Won-Mo Yang, Min-Cheol Kang, Kellen Cristina da Cruz Rodrigues, Ahmet Aydogan, Ji A Seo, Natalia F. Mendes, Min-Seon Kim, Fatima Ezzahra Timzoura, Michael J. Holtzman, Maria Lehtinen, Vincent Prevot, and Young-Bum Kim. Lrp1 mediates leptin transport by coupling with the short-form leptin receptor in the choroid plexus. bioRxiv, Jul 2023. URL: https://doi.org/10.1101/2023.07.03.547520, doi:10.1101/2023.07.03.547520. This article has 4 citations.
(farooqi2007clinicalandmolecular pages 1-2): I. Sadaf Farooqi, Teresia Wangensteen, Stephan Collins, Wendy Kimber, Giuseppe Matarese, Julia M. Keogh, Emma Lank, Bill Bottomley, Judith Lopez-Fernandez, Ivan Ferraz-Amaro, Mehul T. Dattani, Oya Ercan, Anne Grethe Myhre, Lars Retterstol, Richard Stanhope, Julie A. Edge, Sheila McKenzie, Nader Lessan, Maryam Ghodsi, Veronica De Rosa, Francesco Perna, Silvia Fontana, Inês Barroso, Dag E. Undlien, and Stephen O'Rahilly. Clinical and molecular genetic spectrum of congenital deficiency of the leptin receptor. The New England journal of medicine, 356 3:237-47, Jan 2007. URL: https://doi.org/10.1056/nejmoa063988, doi:10.1056/nejmoa063988. This article has 1017 citations and is from a highest quality peer-reviewed journal.
(farooqi2007clinicalandmolecular pages 5-6): I. Sadaf Farooqi, Teresia Wangensteen, Stephan Collins, Wendy Kimber, Giuseppe Matarese, Julia M. Keogh, Emma Lank, Bill Bottomley, Judith Lopez-Fernandez, Ivan Ferraz-Amaro, Mehul T. Dattani, Oya Ercan, Anne Grethe Myhre, Lars Retterstol, Richard Stanhope, Julie A. Edge, Sheila McKenzie, Nader Lessan, Maryam Ghodsi, Veronica De Rosa, Francesco Perna, Silvia Fontana, Inês Barroso, Dag E. Undlien, and Stephen O'Rahilly. Clinical and molecular genetic spectrum of congenital deficiency of the leptin receptor. The New England journal of medicine, 356 3:237-47, Jan 2007. URL: https://doi.org/10.1056/nejmoa063988, doi:10.1056/nejmoa063988. This article has 1017 citations and is from a highest quality peer-reviewed journal.
(qamar2024setmelanotideamelanocortin4 pages 6-7): Sulmaaz Qamar, Ritwika Mallik, and Janine Makaronidis. Setmelanotide: a melanocortin-4 receptor agonist for the treatment of severe obesity due to hypothalamic dysfunction. touchREVIEWS in Endocrinology, Oct 2024. URL: https://doi.org/10.17925/ee.2024.20.2.9, doi:10.17925/ee.2024.20.2.9. This article has 16 citations.
(NCT03287960 chunk 1): Setmelanotide for the Treatment of Leptin Receptor (LEPR) Deficiency Obesity. Rhythm Pharmaceuticals, Inc.. 2018. ClinicalTrials.gov Identifier: NCT03287960