{"doi":"10.4049/jimmunol.167.8.4504","title":"An Ancient Lectin-Dependent Complement System in an Ascidian: Novel Lectin Isolated from the Plasma of the Solitary Ascidian,\n                    <i>Halocynthia roretzi</i>","abstract":"<jats:title>Abstract</jats:title>\n                  <jats:p>Mannose-binding lectin (MBL) is a C-type lectin involved in the first line of host defense against pathogens and it requires MBL-associated serine protease (MASP) for activation of the complement lectin pathway. To elucidate the origin and evolution of MBL, MBL-like lectin was isolated from the plasma of a urochordate, the solitary ascidian Halocynthia roretzi, using affinity chromatography on a yeast mannan-Sepharose. SDS-PAGE of the eluted proteins revealed a major band of ∼36 kDa (p36). p36 cDNA was cloned from an ascidian hepatopancreas cDNA library. Sequence analysis revealed that the carboxy-terminal half of the ascidian lectin contains a carbohydrate recognition domain (CRD) that is homologous to C-type lectin, but it lacks a collagen-like domain that is present in mammalian MBLs. Purified p36 binds specifically to glucose but not to mannose or N-acetylglucosamine, and it was designated glucose-binding lectin (GBL). The two ascidian MASPs associated with GBL activate ascidian C3, which had been reported to act as an opsonin. The removal of GBL-MASPs complex from ascidian plasma using Ab against GBL inhibits C3-dependent phagocytosis. These observations strongly suggest that GBL acts as a recognition molecule and that the primitive complement system, consisting of the lectin-proteases complex and C3, played a major role in innate immunity before the evolution of an adaptive immune system in vertebrates.</jats:p>","journal":"The Journal of Immunology","year":2001,"id":17523,"datarank":5.474072082507519,"base_score":4.882801922586371,"endowment":4.882801922586371,"self_citation_contribution":0.7324202883879557,"citation_network_contribution":4.741651794119563,"self_endowment_contribution":0.7324202883879557,"citer_contribution":4.741651794119563,"corpus_percentile":null,"corpus_rank":null,"citation_count":131,"citer_count":120,"citers_with_citation_signal":109,"citers_with_endowment":109,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":125057,"name":"Akira Kenjo","orcid":null,"position":1,"is_corresponding":false},{"id":125058,"name":"Kaoru Azumi","orcid":null,"position":2,"is_corresponding":false},{"id":125059,"name":"Gota Ohi","orcid":null,"position":3,"is_corresponding":false},{"id":123115,"name":"Minoru Takahashi","orcid":"0000-0001-7625-2448","position":4,"is_corresponding":false},{"id":125060,"name":"Reiji Kasukawa","orcid":null,"position":5,"is_corresponding":false},{"id":125062,"name":"Narumi Ichikawa","orcid":null,"position":6,"is_corresponding":false},{"id":123843,"name":"Munehiro Nakata","orcid":null,"position":7,"is_corresponding":false},{"id":123988,"name":"Tsuguo Mizuochi","orcid":null,"position":8,"is_corresponding":false},{"id":122927,"name":"Misao Matsushita","orcid":null,"position":9,"is_corresponding":false},{"id":123106,"name":"Yuichi Endo","orcid":null,"position":10,"is_corresponding":false},{"id":122928,"name":"Teizo Fujita","orcid":null,"position":11,"is_corresponding":false},{"id":123924,"name":"Hideharu Sekine","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"base_score":4.882801922586371,"endowment":4.882801922586371,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"11591777","pmcid":null,"openalex_id":"https://openalex.org/W2131737832","authors":[],"funders":[],"total_grants":0,"fwci":2.9962,"citation_percentile":0.92162748,"influential_citations":3,"citation_trend":[{"year":2012,"count":4},{"year":2013,"count":5},{"year":2014,"count":1},{"year":2015,"count":6},{"year":2016,"count":4},{"year":2017,"count":4},{"year":2018,"count":2},{"year":2019,"count":3},{"year":2020,"count":2},{"year":2021,"count":3},{"year":2022,"count":9},{"year":2023,"count":2},{"year":2024,"count":3},{"year":2025,"count":3},{"year":2026,"count":1}],"oa_status":"closed","license":"https://academic.oup.com/pages/standard-publication-reuse-rights","oa_locations":[{"url":"https://journals.aai.org/jimmunol/article-pdf/167/8/4504/1143421/4504.pdf","host_type":"BRONZE"},{"url":"https://academic.oup.com/jimmunol/article-pdf/167/8/4504/62539811/4504.pdf","host_type":"publisher"},{"url":"https://doi.org/10.4049/jimmunol.167.8.4504","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/11591777","host_type":"repository"}],"fields_of_study":["Invertebrate Immune Response Mechanisms","Complement system in diseases","Insect symbiosis and bacterial influences","Biology","Medicine","Amino Acid Sequence","Animals","Carrier Proteins","Collectins","Complement Activation","Complement C3","Digestive System","Evolution, Molecular","Gene Library","Lectins","Mannose-Binding Protein-Associated Serine Proteases","Molecular Sequence Data","Protein Binding","Sequence Homology, Amino Acid","Serine Endopeptidases","Urochordata"],"mesh_terms":["Amino Acid Sequence","Animals","Carrier Proteins","Complement Activation","Complement C3","Digestive System","Molecular Sequence Data","Protein Binding","Serine Endopeptidases","Urochordata","Gene Library","Sequence Homology, Amino Acid","Evolution, Molecular","Lectins","Collectins","Mannose-Binding Protein-Associated Serine Proteases"],"keywords":["Lectin","Mannan-binding lectin","Lectin pathway","C-type lectin","Complement system","Ficolin","Biology","Collectin","Innate immune system","MASP1","Complementary DNA","Mannose","Molecular biology","Classical complement pathway","Cell biology","Biochemistry","Serine protease","Gene","Immune system","Protease","Receptor","Genetics"],"sdg_mappings":[{"sdg_number":0,"sdg_label":"Life in Land"}],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-06-02T19:14:37.090371Z","pmid":null,"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,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}