{"doi":"10.1016/j.jbc.2024.107267","title":"Phospholamban inhibits the cardiac calcium pump by interrupting an allosteric activation pathway","abstract":"Phospholamban (PLB) is a transmembrane micropeptide that regulates the Ca 2+ pump SERCA in cardiac muscle, but the physical mechanism of this regulation remains poorly understood. PLB reduces the Ca 2+ sensitivity of active SERCA, increasing the Ca 2+ concentration required for pump cycling. However, PLB does not decrease Ca 2+ binding to SERCA when ATP is absent, suggesting PLB does not inhibit SERCA Ca 2+ affinity. The prevailing explanation for these seemingly conflicting results is that PLB slows transitions in the SERCA enzymatic cycle associated with Ca 2+ binding, altering transport Ca 2+ dependence without actually affecting the equilibrium binding affinity of the Ca 2+ -coordinating sites. Here, we consider another hypothesis, that measurements of Ca 2+ binding in the absence of ATP overlook important allosteric effects of nucleotide binding that increase SERCA Ca 2+ binding affinity. We speculated that PLB inhibits SERCA by reversing this allostery. To test this, we used a fluorescent SERCA biosensor to quantify the Ca 2+ affinity of non-cycling SERCA in the presence and absence of a non-hydrolyzable ATP-analog, AMPPCP. Nucleotide activation increased SERCA Ca 2+ affinity, and this effect was reversed by co-expression of PLB. Interestingly, PLB had no effect on Ca 2+ affinity in the absence of nucleotide. These results reconcile the previous conflicting observations from ATPase assays versus Ca 2+ binding assays. Moreover, structural analysis of SERCA revealed a novel allosteric pathway connecting the ATP- and Ca 2+ -binding sites. We propose this pathway is disrupted by PLB binding. Thus, PLB reduces the equilibrium Ca 2+ affinity of SERCA by interrupting allosteric activation of the pump by ATP.","journal":"Journal of Biological Chemistry","year":2024,"id":432128,"datarank":0.41588830833596724,"base_score":2.772588722239781,"endowment":2.772588722239781,"self_citation_contribution":0.41588830833596724,"citation_network_contribution":0.0,"self_endowment_contribution":0.41588830833596724,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":15,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9533,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2024-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":406901,"name":"Jaroslava Šeflová","orcid":"0000-0001-5486-0864","position":1,"is_corresponding":false},{"id":561862,"name":"Ellen E. Cho","orcid":"0000-0001-7953-2736","position":2,"is_corresponding":false},{"id":1189678,"name":"Konark Bisht","orcid":"0000-0001-9161-9789","position":3,"is_corresponding":false},{"id":486618,"name":"Himanshu Khandelia","orcid":"0000-0001-9913-6394","position":4,"is_corresponding":false},{"id":650117,"name":"L. Michel Espinoza‐Fonseca","orcid":"0009-0007-1006-6504","position":5,"is_corresponding":false},{"id":406903,"name":"Seth L. Robia","orcid":"0000-0002-1193-9510","position":6,"is_corresponding":false},{"id":406900,"name":"Sean R. Cleary","orcid":"0000-0002-4789-0042","position":0,"is_corresponding":true}],"reference_count":72,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-19T01:59:35.267142Z","pmid":"38583863","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}