{"gene":"LRRC52","run_date":"2026-06-10T02:59:50","timeline":{"discoveries":[{"year":2011,"finding":"LRRC52 was identified as a Slo3-associating auxiliary subunit in mouse testis that shifts Slo3 gating to voltages and pH values similar to native KSper current. LRRC52 protein expression was found to be critically dependent on the presence of Slo3, as it was markedly diminished from Slo3-/- testis and completely absent from Slo3-/- sperm.","method":"Heterologous expression, electrophysiology (patch clamp), western blotting, immunodetection in Slo3 knockout mouse tissue","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal functional expression, KO mouse validation, multiple orthogonal methods, replicated across labs","pmids":["22084117"],"is_preprint":false},{"year":2012,"finding":"LRRC52 functions as a BK channel (SLO1) auxiliary subunit (γ2 subunit) producing a ~100 mV negative shift in voltage dependence of BK channel activation in the absence of calcium, classifying it as a member of the γ family of BK auxiliary proteins distinct from β subunits.","method":"Heterologous expression in Xenopus oocytes or HEK cells with electrophysiology","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — functional electrophysiology with multiple LRRC paralogs compared, replicated by multiple independent labs","pmids":["22547800"],"is_preprint":false},{"year":2012,"finding":"Human SLO3 channel expression and functional properties (pH-dependent activation) are modulated by LRRC52 as a testis-specific accessory subunit in heterologous expression systems.","method":"Electrophysiology in heterologous system (patch clamp), co-expression of human SLO3 with LRRC52","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — functional electrophysiology with human SLO3, complemented by crystal structure of gating ring, consistent with mouse data","pmids":["23129643"],"is_preprint":false},{"year":2015,"finding":"Genetic knockout of LRRC52 in mice results in severely impaired fertility. KSPER current activation in LRRC52-null sperm requires more positive voltages and higher pH than in wild-type, establishing LRRC52 as a critical gating modifier of the native KSPER channel required for physiological sperm function.","method":"LRRC52 knockout mouse model, patch-clamp electrophysiology of sperm, in vitro fertilization assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO mouse with defined electrophysiological and fertility phenotype, multiple orthogonal methods","pmids":["25675513"],"is_preprint":false},{"year":2019,"finding":"LRRC52 regulates BK channel function and localization in mouse cochlear inner hair cells (IHCs). Knockout of LRRC52 shifted BK current activation by more than +200 mV and disrupted BK channel clustering/localization in IHCs, suggesting LRRC52 stabilizes a macromolecular complex required for both gating at negative potentials and correct spatial positioning.","method":"LRRC52 knockout mouse, patch-clamp electrophysiology, immunofluorescence/confocal imaging of BK channel localization in IHCs","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO mouse with both functional electrophysiology and localization phenotype, multiple orthogonal methods","pmids":["31451634"],"is_preprint":false},{"year":2019,"finding":"LRRC52 (γ2 subunit) co-localizes with BKα within ≤40 nm in mouse IHC necks as demonstrated by in situ proximity ligation assay. LRRC52 protein expression requires the presence of both BKα and Cav1.3, as LRRC52 was absent in BKα KO and Cav1.3 KO IHCs.","method":"Nested PCR, confocal immunohistochemistry, in situ proximity ligation assay, BKα and Cav1.3 knockout mouse models","journal":"FASEB journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — proximity ligation assay plus KO validation, multiple orthogonal methods in single study","pmids":["31348683"],"is_preprint":false},{"year":2020,"finding":"The Slo3/LRRC52 complex retains sensitivity to phosphoinositides (PtdIns(4,5)P2) similar to Slo3 alone; VSP-mediated depletion of PtdIns(4,5)P2 inhibits Slo3+LRRC52 currents in Xenopus oocytes.","method":"Heterologous expression in Xenopus oocytes, voltage-sensing phosphatase (VSP)-mediated phosphoinositide manipulation, electrophysiology","journal":"Channels (Austin, Tex.)","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — functional electrophysiology in heterologous system, single lab, single method","pmids":["32564653"],"is_preprint":false},{"year":2022,"finding":"The LRR domain of LRRC52 (γ2) is localized extracellularly. N-glycosylation of LRRC52 is required for its total protein expression; blockade of N-glycosylation drastically reduces total expression of the γ2 subunit. The LRR domain is non-essential for the maximal channel-gating modulatory effect.","method":"Cell surface protein immunoprecipitation, molecular dynamics simulation, N-glycosylation mutants and enzymatic blockade, expression analysis by western blot","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (IP, mutagenesis, enzymatic blockade) in single lab","pmids":["35104503"],"is_preprint":false},{"year":2024,"finding":"A polyclonal antibody (LID1) targeting an extracellular segment of LRRC52 co-immunoprecipitated with mSlo3 and inhibited native mKSper and hKSper currents, supporting that LRRC52 is a functional component of human KSper. LID1 treatment depolarized sperm membrane potential, impaired Ca2+ signaling, sperm motility, and acrosome reaction in both mouse and human sperm.","method":"Co-immunoprecipitation, patch-clamp electrophysiology of mouse and human sperm, antibody inhibition experiments, Ca2+ imaging, motility and acrosome reaction assays","journal":"Biology of reproduction","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP plus functional electrophysiology in native cells plus multiple phenotypic assays, single lab","pmids":["38267364"],"is_preprint":false},{"year":2024,"finding":"Inhibition of hKSper (containing LRRC52) by the LRRC52 antibody LID1 (as well as pharmacological blockers) causes membrane potential depolarization of ~25-30 mV and flagellar pH acidification in human sperm. Pre-incubation with high K+ solution abolished both effects, demonstrating that hKSper regulates flagellar pH homeostasis through its control of membrane potential.","method":"Single-cell pH fluorescent recording (pHrodo Red), patch-clamp electrophysiology, pharmacological inhibition and antibody blockade in human sperm","journal":"Andrology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple inhibitors plus ionic rescue experiment, single lab, multiple orthogonal methods","pmids":["39498893"],"is_preprint":false},{"year":2024,"finding":"Coexpression of LRRC52 with IHC-specific BK channel splice variants (STREX/exon2 + alt9) significantly shifts voltage dependence at 0 [Ca2+]i, contributing to Ca2+-independent activation of BK channels in IHCs. The combination of LRRC52, specific splice isoforms, and mechanical force additively accounts for the Ca2+-independent activation of BK channels in IHCs.","method":"Heterologous expression with specific BK splice variants and LRRC52, patch-clamp electrophysiology, IHC-specific BK conditional knockout mouse for auditory phenotype","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — heterologous functional reconstitution with specific isoforms plus KO mouse, single lab","pmids":["39515584"],"is_preprint":false}],"current_model":"LRRC52 is a leucine-rich repeat-containing auxiliary γ2 subunit that associates with both SLO3 (in sperm) and SLO1/BK channels (in cochlear inner hair cells and other tissues), producing large negative shifts (~100 mV) in voltage dependence of channel activation through stabilization of a macromolecular complex; in sperm, it is required for physiological KSper gating under capacitation conditions, flagellar pH homeostasis, and male fertility, while in cochlear IHCs it is essential for Ca2+-independent BK channel activation at negative membrane potentials and for correct BK channel subcellular localization."},"narrative":{"mechanistic_narrative":"LRRC52 is a leucine-rich repeat-containing auxiliary subunit (the BK γ2 subunit) that associates with Slo-family potassium channels to drive large negative shifts in their voltage dependence of activation, thereby enabling channel opening at physiological membrane potentials [PMID:22084117, PMID:22547800]. In testis, it associates with the sperm-specific SLO3 channel and shifts its gating to the voltages and pH characteristic of the native KSper current; its own expression is critically dependent on the presence of SLO3 [PMID:22084117, PMID:23129643]. As a member of the γ family of BK auxiliary proteins—distinct from β subunits—LRRC52 produces a ~100 mV hyperpolarizing shift in the voltage dependence of SLO1/BK channel activation in the absence of calcium [PMID:22547800]. Genetic ablation in mice establishes its physiological roles: LRRC52-null sperm require more positive voltages and higher pH for KSper activation, and the mice are severely subfertile [PMID:25675513]; in cochlear inner hair cells, knockout shifts BK current activation by more than +200 mV and disrupts BK channel clustering, identifying LRRC52 as essential for Ca2+-independent BK activation at negative potentials and for correct channel localization [PMID:31451634, PMID:39515584]. LRRC52 localizes within ≤40 nm of BKα in IHC necks and requires both BKα and Cav1.3 for its expression, consistent with assembly into a stable macromolecular channel complex [PMID:31348683]. Antibody targeting of its extracellular segment inhibits native mouse and human KSper, depolarizing the sperm membrane, acidifying flagellar pH, and impairing motility and the acrosome reaction—defining KSper-dependent control of membrane potential and pH homeostasis as a requirement for human sperm function [PMID:38267364, PMID:39498893]. Structurally, the LRR domain is extracellular and dispensable for maximal gating modulation, while N-glycosylation is required for full protein expression [PMID:35104503].","teleology":[{"year":2011,"claim":"Established LRRC52 as the long-sought auxiliary subunit that reconciles SLO3's heterologous gating with the native sperm KSper current, answering why SLO3 alone failed to recapitulate KSper.","evidence":"Heterologous co-expression with electrophysiology plus western blotting in Slo3 knockout mouse testis","pmids":["22084117"],"confidence":"High","gaps":["Did not resolve the structural interface between LRRC52 and SLO3","Mechanism by which SLO3 controls LRRC52 protein stability not defined"]},{"year":2012,"claim":"Defined LRRC52 as the BK channel γ2 subunit, showing it acts on SLO1/BK (not only SLO3) and classifying it within a distinct γ family of auxiliary proteins separate from β subunits.","evidence":"Heterologous expression in oocytes/HEK cells with electrophysiology, comparing LRRC paralogs","pmids":["22547800","23129643"],"confidence":"High","gaps":["Native tissue context of BK modulation not yet established in 2012","Stoichiometry of LRRC52:channel assembly not determined"]},{"year":2015,"claim":"Demonstrated through gene knockout that LRRC52 is physiologically required for normal KSper gating and male fertility, moving it from a heterologous modulator to an essential native component.","evidence":"LRRC52 knockout mouse with sperm patch-clamp electrophysiology and in vitro fertilization assays","pmids":["25675513"],"confidence":"High","gaps":["Did not address non-testis roles of LRRC52","Downstream consequences for sperm pH or motility not directly measured"]},{"year":2019,"claim":"Extended LRRC52 function to cochlear inner hair cells, revealing it is required both for Ca2+-independent BK gating at negative potentials and for correct BK channel clustering, implicating it in macromolecular complex assembly.","evidence":"LRRC52 knockout mouse with patch-clamp and confocal localization, plus proximity ligation assay and BKα/Cav1.3 knockout validation","pmids":["31451634","31348683"],"confidence":"High","gaps":["Molecular basis for LRRC52-dependent channel clustering unresolved","How Cav1.3 controls LRRC52 expression not mechanistically defined"]},{"year":2020,"claim":"Addressed whether LRRC52 alters lipid regulation of the channel, showing the Slo3/LRRC52 complex retains PtdIns(4,5)P2 sensitivity comparable to Slo3 alone.","evidence":"Heterologous oocyte expression with VSP-mediated phosphoinositide depletion and electrophysiology","pmids":["32564653"],"confidence":"Medium","gaps":["Single-lab heterologous result not confirmed in native sperm","Did not map a phosphoinositide interaction site"]},{"year":2022,"claim":"Defined the structural topology and biogenesis requirements of LRRC52, placing the LRR domain extracellularly, showing N-glycosylation is needed for full expression, and that the LRR domain is dispensable for maximal gating modulation.","evidence":"Cell-surface immunoprecipitation, N-glycosylation mutants and enzymatic blockade, molecular dynamics, western blot","pmids":["35104503"],"confidence":"Medium","gaps":["Functional role of the extracellular LRR domain remains unexplained","Which transmembrane/intracellular segment mediates gating modulation not pinpointed"]},{"year":2024,"claim":"Validated LRRC52 as a functional component of human KSper and linked KSper activity to sperm physiology, showing antibody blockade of its extracellular segment depolarizes membrane potential, acidifies flagellar pH, and impairs motility, Ca2+ signaling and the acrosome reaction.","evidence":"Co-immunoprecipitation, patch-clamp of mouse and human sperm, antibody (LID1) inhibition, single-cell pH and Ca2+ imaging, motility and acrosome assays, with high-K+ ionic rescue","pmids":["38267364","39498893"],"confidence":"High","gaps":["Causal contribution of LRRC52 to human male infertility in patients not established","Whether LID1 acts directly on LRRC52 or sterically on the complex not fully resolved"]},{"year":2024,"claim":"Reconstituted the determinants of Ca2+-independent BK activation in IHCs, showing LRRC52 acts together with IHC-specific BK splice isoforms and mechanical force additively to shift voltage dependence at zero calcium.","evidence":"Heterologous expression of LRRC52 with STREX/exon2+alt9 BK splice variants, patch-clamp, and IHC-specific BK conditional knockout for auditory phenotype","pmids":["39515584"],"confidence":"Medium","gaps":["Relative in vivo contributions of LRRC52 versus splicing versus force not quantified","Single-lab reconstitution"]},{"year":null,"claim":"The structural interface of LRRC52 with SLO1/SLO3 and the mechanism by which it produces large voltage-dependence shifts and channel clustering remain undefined.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No high-resolution structure of an LRRC52-channel complex in the corpus","Assembly stoichiometry and the segment mediating gating modulation unmapped","Role of LRRC52 in human disease/infertility genetics untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0,1,2,3,4]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[1,3]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[5,7]}],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[3,8]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[4,10]}],"complexes":["SLO3/LRRC52 (KSper) channel complex","SLO1/BK channel complex"],"partners":["SLO3","KCNMA1","CACNA1D"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8N7C0","full_name":"Leucine-rich repeat-containing protein 52","aliases":["BK channel auxiliary gamma subunit LRRC52"],"length_aa":313,"mass_kda":35.1,"function":"Auxiliary protein of the large-conductance, voltage and calcium-activated potassium channel (BK alpha). Modulates gating properties by producing a marked shift in the BK channel's voltage dependence of activation in the hyperpolarizing direction, and in the absence of calcium. KCNU1 channel auxiliary protein. Modulates KCNU1 gating properties","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q8N7C0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/LRRC52","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/LRRC52","total_profiled":1310},"omim":[{"mim_id":"615218","title":"LEUCINE-RICH REPEAT-CONTAINING PROTEIN 52; LRRC52","url":"https://www.omim.org/entry/615218"},{"mim_id":"615215","title":"POTASSIUM CHANNEL, SUBFAMILY U, MEMBER 1; KCNU1","url":"https://www.omim.org/entry/615215"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enriched","tissue_distribution":"Detected in some","driving_tissues":[{"tissue":"testis","ntpm":15.6}],"url":"https://www.proteinatlas.org/search/LRRC52"},"hgnc":{"alias_symbol":["FLJ25811"],"prev_symbol":[]},"alphafold":{"accession":"Q8N7C0","domains":[{"cath_id":"3.80.10.10","chopping":"27-180","consensus_level":"medium","plddt":95.6287,"start":27,"end":180},{"cath_id":"1.20.5","chopping":"243-278","consensus_level":"medium","plddt":92.9814,"start":243,"end":278}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8N7C0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8N7C0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8N7C0-F1-predicted_aligned_error_v6.png","plddt_mean":86.94},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=LRRC52","jax_strain_url":"https://www.jax.org/strain/search?query=LRRC52"},"sequence":{"accession":"Q8N7C0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8N7C0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8N7C0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8N7C0"}},"corpus_meta":[{"pmid":"22547800","id":"PMC_22547800","title":"BK potassium channel modulation by leucine-rich repeat-containing proteins.","date":"2012","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/22547800","citation_count":188,"is_preprint":false},{"pmid":"31665287","id":"PMC_31665287","title":"Human sperm ion channel (dys)function: implications for fertilization.","date":"2019","source":"Human reproduction update","url":"https://pubmed.ncbi.nlm.nih.gov/31665287","citation_count":79,"is_preprint":false},{"pmid":"22084117","id":"PMC_22084117","title":"LRRC52 (leucine-rich-repeat-containing protein 52), a testis-specific auxiliary subunit of the alkalization-activated Slo3 channel.","date":"2011","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/22084117","citation_count":72,"is_preprint":false},{"pmid":"25360119","id":"PMC_25360119","title":"Regulation of BK channels by auxiliary γ subunits.","date":"2014","source":"Frontiers in physiology","url":"https://pubmed.ncbi.nlm.nih.gov/25360119","citation_count":63,"is_preprint":false},{"pmid":"27052499","id":"PMC_27052499","title":"Depolarization of sperm membrane potential is a common feature of men with subfertility and is associated with low fertilization rate at IVF.","date":"2016","source":"Human reproduction (Oxford, England)","url":"https://pubmed.ncbi.nlm.nih.gov/27052499","citation_count":58,"is_preprint":false},{"pmid":"23129643","id":"PMC_23129643","title":"Functional and structural analysis of the human SLO3 pH- and voltage-gated K+ channel.","date":"2012","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/23129643","citation_count":54,"is_preprint":false},{"pmid":"25675513","id":"PMC_25675513","title":"SLO3 auxiliary subunit LRRC52 controls gating of sperm KSPER currents and is critical for normal fertility.","date":"2015","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/25675513","citation_count":48,"is_preprint":false},{"pmid":"31451634","id":"PMC_31451634","title":"LRRC52 regulates BK channel function and localization in mouse cochlear inner hair cells.","date":"2019","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/31451634","citation_count":24,"is_preprint":false},{"pmid":"34980136","id":"PMC_34980136","title":"Homozygous mutation in SLO3 leads to severe asthenoteratozoospermia due to acrosome hypoplasia and mitochondrial sheath malformations.","date":"2022","source":"Reproductive biology and endocrinology : RB&E","url":"https://pubmed.ncbi.nlm.nih.gov/34980136","citation_count":23,"is_preprint":false},{"pmid":"35014034","id":"PMC_35014034","title":"The LRRC family of BK channel regulatory subunits: potential roles in health and disease.","date":"2022","source":"The Journal of physiology","url":"https://pubmed.ncbi.nlm.nih.gov/35014034","citation_count":21,"is_preprint":false},{"pmid":"35039093","id":"PMC_35039093","title":"Epigenetics of single-site and multi-site atherosclerosis in African Americans from the Genetic Epidemiology Network of Arteriopathy (GENOA).","date":"2022","source":"Clinical epigenetics","url":"https://pubmed.ncbi.nlm.nih.gov/35039093","citation_count":13,"is_preprint":false},{"pmid":"35104503","id":"PMC_35104503","title":"The leucine-rich repeat domains of BK channel auxiliary γ subunits regulate their expression, trafficking, and channel-modulation functions.","date":"2022","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/35104503","citation_count":12,"is_preprint":false},{"pmid":"36132147","id":"PMC_36132147","title":"Use of long non-coding RNAs for the molecular diagnosis of papillary thyroid cancer.","date":"2022","source":"Frontiers in oncology","url":"https://pubmed.ncbi.nlm.nih.gov/36132147","citation_count":9,"is_preprint":false},{"pmid":"31496875","id":"PMC_31496875","title":"Onion peel extract and its constituent, quercetin inhibits human Slo3 in a pH and calcium dependent manner.","date":"2019","source":"The Korean journal of physiology & pharmacology : official journal of the Korean Physiological Society and the Korean Society of Pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/31496875","citation_count":8,"is_preprint":false},{"pmid":"31855284","id":"PMC_31855284","title":"LRRC52-AS1 is associated with clinical progression and regulates cell migration and invasion in papillary thyroid cancer.","date":"2020","source":"Clinical and experimental pharmacology & physiology","url":"https://pubmed.ncbi.nlm.nih.gov/31855284","citation_count":6,"is_preprint":false},{"pmid":"31348683","id":"PMC_31348683","title":"Expression of the LRRC52 γ subunit (γ2) may provide Ca2+-independent activation of BK currents in mouse inner hair cells.","date":"2019","source":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","url":"https://pubmed.ncbi.nlm.nih.gov/31348683","citation_count":4,"is_preprint":false},{"pmid":"38267364","id":"PMC_38267364","title":"LRRC52 is likely a functional component of human KSper†.","date":"2024","source":"Biology of reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/38267364","citation_count":4,"is_preprint":false},{"pmid":"32564653","id":"PMC_32564653","title":"The Slo3/Lrrc52 complex is sensitive to phosphoinositides.","date":"2020","source":"Channels (Austin, Tex.)","url":"https://pubmed.ncbi.nlm.nih.gov/32564653","citation_count":2,"is_preprint":false},{"pmid":"38492360","id":"PMC_38492360","title":"LncRNAs associated with lymph node metastasis in thyroid cancer based on TCGA database.","date":"2024","source":"Pathology, research and practice","url":"https://pubmed.ncbi.nlm.nih.gov/38492360","citation_count":2,"is_preprint":false},{"pmid":"39498893","id":"PMC_39498893","title":"Pharmacological inhibition of KSper impairs flagellar pH homeostasis of human spermatozoa.","date":"2024","source":"Andrology","url":"https://pubmed.ncbi.nlm.nih.gov/39498893","citation_count":1,"is_preprint":false},{"pmid":"39515584","id":"PMC_39515584","title":"The mechanism of Ca2+-independent activation of BKCa channels in mouse inner hair cells and the crucial role of the BK channels in auditory perception.","date":"2024","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/39515584","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":14617,"output_tokens":2771,"usd":0.042708,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9997,"output_tokens":3270,"usd":0.065867,"stage2_stop_reason":"end_turn"},"total_usd":0.108575,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2011,\n      \"finding\": \"LRRC52 was identified as a Slo3-associating auxiliary subunit in mouse testis that shifts Slo3 gating to voltages and pH values similar to native KSper current. LRRC52 protein expression was found to be critically dependent on the presence of Slo3, as it was markedly diminished from Slo3-/- testis and completely absent from Slo3-/- sperm.\",\n      \"method\": \"Heterologous expression, electrophysiology (patch clamp), western blotting, immunodetection in Slo3 knockout mouse tissue\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal functional expression, KO mouse validation, multiple orthogonal methods, replicated across labs\",\n      \"pmids\": [\"22084117\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"LRRC52 functions as a BK channel (SLO1) auxiliary subunit (γ2 subunit) producing a ~100 mV negative shift in voltage dependence of BK channel activation in the absence of calcium, classifying it as a member of the γ family of BK auxiliary proteins distinct from β subunits.\",\n      \"method\": \"Heterologous expression in Xenopus oocytes or HEK cells with electrophysiology\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — functional electrophysiology with multiple LRRC paralogs compared, replicated by multiple independent labs\",\n      \"pmids\": [\"22547800\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Human SLO3 channel expression and functional properties (pH-dependent activation) are modulated by LRRC52 as a testis-specific accessory subunit in heterologous expression systems.\",\n      \"method\": \"Electrophysiology in heterologous system (patch clamp), co-expression of human SLO3 with LRRC52\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — functional electrophysiology with human SLO3, complemented by crystal structure of gating ring, consistent with mouse data\",\n      \"pmids\": [\"23129643\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Genetic knockout of LRRC52 in mice results in severely impaired fertility. KSPER current activation in LRRC52-null sperm requires more positive voltages and higher pH than in wild-type, establishing LRRC52 as a critical gating modifier of the native KSPER channel required for physiological sperm function.\",\n      \"method\": \"LRRC52 knockout mouse model, patch-clamp electrophysiology of sperm, in vitro fertilization assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO mouse with defined electrophysiological and fertility phenotype, multiple orthogonal methods\",\n      \"pmids\": [\"25675513\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"LRRC52 regulates BK channel function and localization in mouse cochlear inner hair cells (IHCs). Knockout of LRRC52 shifted BK current activation by more than +200 mV and disrupted BK channel clustering/localization in IHCs, suggesting LRRC52 stabilizes a macromolecular complex required for both gating at negative potentials and correct spatial positioning.\",\n      \"method\": \"LRRC52 knockout mouse, patch-clamp electrophysiology, immunofluorescence/confocal imaging of BK channel localization in IHCs\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO mouse with both functional electrophysiology and localization phenotype, multiple orthogonal methods\",\n      \"pmids\": [\"31451634\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"LRRC52 (γ2 subunit) co-localizes with BKα within ≤40 nm in mouse IHC necks as demonstrated by in situ proximity ligation assay. LRRC52 protein expression requires the presence of both BKα and Cav1.3, as LRRC52 was absent in BKα KO and Cav1.3 KO IHCs.\",\n      \"method\": \"Nested PCR, confocal immunohistochemistry, in situ proximity ligation assay, BKα and Cav1.3 knockout mouse models\",\n      \"journal\": \"FASEB journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — proximity ligation assay plus KO validation, multiple orthogonal methods in single study\",\n      \"pmids\": [\"31348683\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"The Slo3/LRRC52 complex retains sensitivity to phosphoinositides (PtdIns(4,5)P2) similar to Slo3 alone; VSP-mediated depletion of PtdIns(4,5)P2 inhibits Slo3+LRRC52 currents in Xenopus oocytes.\",\n      \"method\": \"Heterologous expression in Xenopus oocytes, voltage-sensing phosphatase (VSP)-mediated phosphoinositide manipulation, electrophysiology\",\n      \"journal\": \"Channels (Austin, Tex.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — functional electrophysiology in heterologous system, single lab, single method\",\n      \"pmids\": [\"32564653\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The LRR domain of LRRC52 (γ2) is localized extracellularly. N-glycosylation of LRRC52 is required for its total protein expression; blockade of N-glycosylation drastically reduces total expression of the γ2 subunit. The LRR domain is non-essential for the maximal channel-gating modulatory effect.\",\n      \"method\": \"Cell surface protein immunoprecipitation, molecular dynamics simulation, N-glycosylation mutants and enzymatic blockade, expression analysis by western blot\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (IP, mutagenesis, enzymatic blockade) in single lab\",\n      \"pmids\": [\"35104503\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"A polyclonal antibody (LID1) targeting an extracellular segment of LRRC52 co-immunoprecipitated with mSlo3 and inhibited native mKSper and hKSper currents, supporting that LRRC52 is a functional component of human KSper. LID1 treatment depolarized sperm membrane potential, impaired Ca2+ signaling, sperm motility, and acrosome reaction in both mouse and human sperm.\",\n      \"method\": \"Co-immunoprecipitation, patch-clamp electrophysiology of mouse and human sperm, antibody inhibition experiments, Ca2+ imaging, motility and acrosome reaction assays\",\n      \"journal\": \"Biology of reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP plus functional electrophysiology in native cells plus multiple phenotypic assays, single lab\",\n      \"pmids\": [\"38267364\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Inhibition of hKSper (containing LRRC52) by the LRRC52 antibody LID1 (as well as pharmacological blockers) causes membrane potential depolarization of ~25-30 mV and flagellar pH acidification in human sperm. Pre-incubation with high K+ solution abolished both effects, demonstrating that hKSper regulates flagellar pH homeostasis through its control of membrane potential.\",\n      \"method\": \"Single-cell pH fluorescent recording (pHrodo Red), patch-clamp electrophysiology, pharmacological inhibition and antibody blockade in human sperm\",\n      \"journal\": \"Andrology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple inhibitors plus ionic rescue experiment, single lab, multiple orthogonal methods\",\n      \"pmids\": [\"39498893\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Coexpression of LRRC52 with IHC-specific BK channel splice variants (STREX/exon2 + alt9) significantly shifts voltage dependence at 0 [Ca2+]i, contributing to Ca2+-independent activation of BK channels in IHCs. The combination of LRRC52, specific splice isoforms, and mechanical force additively accounts for the Ca2+-independent activation of BK channels in IHCs.\",\n      \"method\": \"Heterologous expression with specific BK splice variants and LRRC52, patch-clamp electrophysiology, IHC-specific BK conditional knockout mouse for auditory phenotype\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — heterologous functional reconstitution with specific isoforms plus KO mouse, single lab\",\n      \"pmids\": [\"39515584\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"LRRC52 is a leucine-rich repeat-containing auxiliary γ2 subunit that associates with both SLO3 (in sperm) and SLO1/BK channels (in cochlear inner hair cells and other tissues), producing large negative shifts (~100 mV) in voltage dependence of channel activation through stabilization of a macromolecular complex; in sperm, it is required for physiological KSper gating under capacitation conditions, flagellar pH homeostasis, and male fertility, while in cochlear IHCs it is essential for Ca2+-independent BK channel activation at negative membrane potentials and for correct BK channel subcellular localization.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"LRRC52 is a leucine-rich repeat-containing auxiliary subunit (the BK \\u03b32 subunit) that associates with Slo-family potassium channels to drive large negative shifts in their voltage dependence of activation, thereby enabling channel opening at physiological membrane potentials [#0, #1]. In testis, it associates with the sperm-specific SLO3 channel and shifts its gating to the voltages and pH characteristic of the native KSper current; its own expression is critically dependent on the presence of SLO3 [#0, #2]. As a member of the \\u03b3 family of BK auxiliary proteins\\u2014distinct from \\u03b2 subunits\\u2014LRRC52 produces a ~100 mV hyperpolarizing shift in the voltage dependence of SLO1/BK channel activation in the absence of calcium [#1]. Genetic ablation in mice establishes its physiological roles: LRRC52-null sperm require more positive voltages and higher pH for KSper activation, and the mice are severely subfertile [#3]; in cochlear inner hair cells, knockout shifts BK current activation by more than +200 mV and disrupts BK channel clustering, identifying LRRC52 as essential for Ca2+-independent BK activation at negative potentials and for correct channel localization [#4, #10]. LRRC52 localizes within \\u226440 nm of BK\\u03b1 in IHC necks and requires both BK\\u03b1 and Cav1.3 for its expression, consistent with assembly into a stable macromolecular channel complex [#5]. Antibody targeting of its extracellular segment inhibits native mouse and human KSper, depolarizing the sperm membrane, acidifying flagellar pH, and impairing motility and the acrosome reaction\\u2014defining KSper-dependent control of membrane potential and pH homeostasis as a requirement for human sperm function [#8, #9]. Structurally, the LRR domain is extracellular and dispensable for maximal gating modulation, while N-glycosylation is required for full protein expression [#7].\",\n  \"teleology\": [\n    {\n      \"year\": 2011,\n      \"claim\": \"Established LRRC52 as the long-sought auxiliary subunit that reconciles SLO3's heterologous gating with the native sperm KSper current, answering why SLO3 alone failed to recapitulate KSper.\",\n      \"evidence\": \"Heterologous co-expression with electrophysiology plus western blotting in Slo3 knockout mouse testis\",\n      \"pmids\": [\"22084117\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not resolve the structural interface between LRRC52 and SLO3\",\n        \"Mechanism by which SLO3 controls LRRC52 protein stability not defined\"\n      ]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Defined LRRC52 as the BK channel \\u03b32 subunit, showing it acts on SLO1/BK (not only SLO3) and classifying it within a distinct \\u03b3 family of auxiliary proteins separate from \\u03b2 subunits.\",\n      \"evidence\": \"Heterologous expression in oocytes/HEK cells with electrophysiology, comparing LRRC paralogs\",\n      \"pmids\": [\"22547800\", \"23129643\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Native tissue context of BK modulation not yet established in 2012\",\n        \"Stoichiometry of LRRC52:channel assembly not determined\"\n      ]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Demonstrated through gene knockout that LRRC52 is physiologically required for normal KSper gating and male fertility, moving it from a heterologous modulator to an essential native component.\",\n      \"evidence\": \"LRRC52 knockout mouse with sperm patch-clamp electrophysiology and in vitro fertilization assays\",\n      \"pmids\": [\"25675513\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not address non-testis roles of LRRC52\",\n        \"Downstream consequences for sperm pH or motility not directly measured\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Extended LRRC52 function to cochlear inner hair cells, revealing it is required both for Ca2+-independent BK gating at negative potentials and for correct BK channel clustering, implicating it in macromolecular complex assembly.\",\n      \"evidence\": \"LRRC52 knockout mouse with patch-clamp and confocal localization, plus proximity ligation assay and BK\\u03b1/Cav1.3 knockout validation\",\n      \"pmids\": [\"31451634\", \"31348683\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Molecular basis for LRRC52-dependent channel clustering unresolved\",\n        \"How Cav1.3 controls LRRC52 expression not mechanistically defined\"\n      ]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Addressed whether LRRC52 alters lipid regulation of the channel, showing the Slo3/LRRC52 complex retains PtdIns(4,5)P2 sensitivity comparable to Slo3 alone.\",\n      \"evidence\": \"Heterologous oocyte expression with VSP-mediated phosphoinositide depletion and electrophysiology\",\n      \"pmids\": [\"32564653\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Single-lab heterologous result not confirmed in native sperm\",\n        \"Did not map a phosphoinositide interaction site\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined the structural topology and biogenesis requirements of LRRC52, placing the LRR domain extracellularly, showing N-glycosylation is needed for full expression, and that the LRR domain is dispensable for maximal gating modulation.\",\n      \"evidence\": \"Cell-surface immunoprecipitation, N-glycosylation mutants and enzymatic blockade, molecular dynamics, western blot\",\n      \"pmids\": [\"35104503\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Functional role of the extracellular LRR domain remains unexplained\",\n        \"Which transmembrane/intracellular segment mediates gating modulation not pinpointed\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Validated LRRC52 as a functional component of human KSper and linked KSper activity to sperm physiology, showing antibody blockade of its extracellular segment depolarizes membrane potential, acidifies flagellar pH, and impairs motility, Ca2+ signaling and the acrosome reaction.\",\n      \"evidence\": \"Co-immunoprecipitation, patch-clamp of mouse and human sperm, antibody (LID1) inhibition, single-cell pH and Ca2+ imaging, motility and acrosome assays, with high-K+ ionic rescue\",\n      \"pmids\": [\"38267364\", \"39498893\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Causal contribution of LRRC52 to human male infertility in patients not established\",\n        \"Whether LID1 acts directly on LRRC52 or sterically on the complex not fully resolved\"\n      ]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Reconstituted the determinants of Ca2+-independent BK activation in IHCs, showing LRRC52 acts together with IHC-specific BK splice isoforms and mechanical force additively to shift voltage dependence at zero calcium.\",\n      \"evidence\": \"Heterologous expression of LRRC52 with STREX/exon2+alt9 BK splice variants, patch-clamp, and IHC-specific BK conditional knockout for auditory phenotype\",\n      \"pmids\": [\"39515584\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Relative in vivo contributions of LRRC52 versus splicing versus force not quantified\",\n        \"Single-lab reconstitution\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The structural interface of LRRC52 with SLO1/SLO3 and the mechanism by which it produces large voltage-dependence shifts and channel clustering remain undefined.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No high-resolution structure of an LRRC52-channel complex in the corpus\",\n        \"Assembly stoichiometry and the segment mediating gating modulation unmapped\",\n        \"Role of LRRC52 in human disease/infertility genetics untested\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0, 1, 2, 3, 4]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [1, 3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [5, 7]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [3, 8]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [4, 10]}\n    ],\n    \"complexes\": [\n      \"SLO3/LRRC52 (KSper) channel complex\",\n      \"SLO1/BK channel complex\"\n    ],\n    \"partners\": [\n      \"SLO3\",\n      \"KCNMA1\",\n      \"CACNA1D\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}