{"doi":"10.17615/dw27-8885","title":"Three Proteins of the U7-Specific Sm Ring Function as the Molecular Ruler To Determine the Site of 3'-End Processing in Mammalian Histone Pre-mRNA","abstract":"Cleavage of histone pre-mRNAs at the 3′ end is guided by the U7 snRNP, which is a component of a larger 3′-end processing complex. To identify other components of this complex, we isolated proteins that stably associate with a fragment of histone pre-mRNA containing all necessary processing elements and a biotin affinity tag at the 5′ end. Among the isolated proteins, we identified three well-characterized processing factors: the stem-loop binding protein (SLBP), which interacts with the stem-loop structure upstream of the cleavage site, and both Lsm11 and SmB, which are components of the U7-specifc Sm ring. We also identified 3′hExo/Eri-1, a multifunctional 3′ exonuclease that is known to trim the 3′ end of 5.8S rRNA. 3′hExo primarily binds to the downstream portion of the stem-loop structure in mature histone mRNA, with the upstream portion being occupied by SLBP. The two proteins bind their respective RNA sites in a cooperative manner, and 3′hExo can recruit SLBP to a mutant stem-loop that itself does not interact with SLBP. UV-cross-linking studies used to characterize interactions within the processing complex demonstrated that 3′hExo also interacts in a U7-dependent manner with unprocessed histone pre-mRNA. However, this interaction is not required for the cleavage reaction. The region between the cleavage site and the U7-binding site interacts with three low-molecular-weight proteins, which were identified as components of the U7-specific Sm core: SmB, SmD3, and Lsm10. These proteins likely rigidify the substrate and function as the molecular ruler in determining the site of cleavage.","journal":"UNC Libraries","year":2020,"id":138972,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.948,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":527973,"name":"X.-c. Yang","orcid":null,"position":1,"is_corresponding":false},{"id":175169,"name":"Z. Dominski","orcid":null,"position":2,"is_corresponding":false},{"id":427058,"name":"W. F. Marzluff","orcid":null,"position":3,"is_corresponding":false},{"id":601709,"name":"M. P. Torres","orcid":null,"position":0,"is_corresponding":true}],"reference_count":0,"raw_metadata":null,"created_at":"2026-07-18T23:17:06.651725Z","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,"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":[]}