{"doi":"10.1101/2020.03.04.977314","title":"Alt-RPL36 downregulates the PI3K-AKT-mTOR signaling pathway by interacting with TMEM24","abstract":"Abstract Thousands of previously unannotated small and alternative open reading frames (alt-ORFs) have recently been revealed in the human genome, and hundreds are now known to be required for cell proliferation. Many alt-ORFs are co-encoded with proteins of known function in multicistronic human genes, but the functions of only a handful are currently known in molecular detail. Using a proteomic strategy for discovery of unannotated short open reading frames in human cells, we report the detection of alt-RPL36, a 148-amino acid protein co-encoded with and overlapping human RPL36 (ribosomal protein L36). Alt-RPL36 partially localizes to the endoplasmic reticulum, where it interacts with TMEM24, which transports the phosphatidylinositol 4,5-bisphosphate [PI(4,5)P 2 ] precursor phosphatidylinositol from the endoplasmic reticulum to the plasma membrane. Knock-out of alt-RPL36 in HEK 293T cells increases PI(4,5)P 2 levels in the plasma membrane, upregulates the PI3K-AKT-mTOR signaling pathway, and increases cell size. Four serine residues of alt-RPL36 are phosphorylated, and mutation of these four serines to alanine abolishes interaction with TMEM24 and, consequently, abolishes alt-RPL36 effects on PI3K signaling and cell size. These results implicate alt-RPL36 as a novel regulator of PI(4,5)P 2 synthesis upstream of the PI3K-AKT-mTOR signaling pathway. More broadly, these results show that the alt-RPL36 transcript can express two sequence-independent polypeptides from overlapping ORFs that regulate the same process – protein synthesis – via different molecular mechanisms (PI3K signaling and ribosome composition), expanding our knowledge of the mechanisms by which multicistronic human genes function.","journal":"bioRxiv (Cold Spring Harbor Laboratory)","year":2020,"id":120102,"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":12,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9491,"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":310477,"name":"Alexandra Khitun","orcid":"0000-0003-4137-0035","position":1,"is_corresponding":false},{"id":371592,"name":"Yang Luo","orcid":"0000-0002-8709-0103","position":2,"is_corresponding":false},{"id":312759,"name":"Zhenkun Na","orcid":null,"position":3,"is_corresponding":false},{"id":558022,"name":"Thitima Phoodokmai","orcid":null,"position":4,"is_corresponding":false},{"id":422927,"name":"Khomkrit Sappakhaw","orcid":null,"position":5,"is_corresponding":false},{"id":310479,"name":"Elizabeth Olatunji","orcid":"0000-0002-1758-4976","position":6,"is_corresponding":false},{"id":421613,"name":"Chayasith Uttamapinant","orcid":"0000-0003-0114-0577","position":7,"is_corresponding":false},{"id":17874,"name":"Sarah A. Slavoff","orcid":"0000-0002-4443-2070","position":8,"is_corresponding":false},{"id":296654,"name":"Xiongwen Cao","orcid":null,"position":0,"is_corresponding":true}],"reference_count":64,"raw_metadata":null,"created_at":"2026-07-18T23:14:33.640077Z","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":[]}