EIF5B

Last update 08 May 2025

Basic Info

Synonyms

DKFZp434I036, eIF-5B, EIF5B

+ [5]

Introduction

Plays a role in translation initiation (PubMed:10659855, PubMed:35732735). Ribosome-dependent GTPase that promotes the joining of the 60S ribosomal subunit to the pre-initiation complex to form the 80S initiation complex with the initiator methionine-tRNA in the P-site base paired to the start codon (PubMed:10659855, PubMed:35732735). Together with eIF1A (EIF1AX), actively orients the initiator methionine-tRNA in a conformation that allows 60S ribosomal subunit joining to form the 80S initiation complex (PubMed:12569173, PubMed:35732735). Is released after formation of the 80S initiation complex (PubMed:35732735). Its GTPase activity is not essential for ribosomal subunits joining, but GTP hydrolysis is needed for eIF1A (EIF1AX) ejection quickly followed by EIF5B release to form elongation-competent ribosomes (PubMed:10659855, PubMed:35732735). In contrast to its procaryotic homolog, does not promote recruitment of Met-rRNA to the small ribosomal subunit (PubMed:10659855).

100 Clinical Results associated with EIF5B

100 Translational Medicine associated with EIF5B

0 Patents (Medical) associated with EIF5B

550

Literatures (Medical) associated with EIF5B

01 Apr 2025·RNA

Role of the sarcin-ricin loop of 23S rRNA in biogenesis of the 50S ribosomal subunit

Article

Author: Moon, Kyung-Mee ; Aval, Sepideh Fakhretaha ; Ortega, Joaquin ; Seffouh, Amal ; Fredrick, Kurt ; Foster, Leonard J

The sarcin-ricin loop (SRL) is one of the most conserved segments of ribosomal RNA (rRNA). Translational GTPases (trGTPases), such as EF-G, EF-Tu, and IF2, form contacts with the SRL that are critical for GTP hydrolysis and factor function. Previous studies showed that expression of 23S rRNA lacking the SRL confers a dominant lethal phenotype inEscherichia coli. Isolated ΔSRL particles were found to be not only inactive in protein synthesis but also incompletely assembled. In particular, block 4 of the subunit, which includes the peptidyl transferase center, remained unfolded. Here, we explore the basis of this assembly defect. We find that 23S rRNA extracted from ΔSRL subunits can be efficiently reconstituted into 50S subunits, and these reconstituted ΔSRL particles exhibit full peptidyl transferase activity. We also further characterize ΔSRL particles purified from cells, using cryo-EM and proteomic methods. These particles lack density for rRNA and r-proteins of block 4, consistent with earlier chemical probing data. Incubation of these particles with excess total r-protein of the large subunit (TP50) fails to restore substantial peptidyl transferase activity. Interestingly, proteomic analysis of control and mutant particles shows an overrepresentation of multiple assembly factors in the ΔSRL case. We propose that one or more GTPases normally act to release assembly factors, and this activity is blocked in the absence of the SRL.

01 Apr 2025·Translational Oncology

Single-cell insights into HNSCC tumor heterogeneity and programmed cell death pathways

Article

Author: Chai, Yuanhao ; Zhang, Ziwei ; Shao, Wenwen ; Zhang, Jianlin

BACKGROUNDHead and neck squamous cell carcinoma (HNSCC) is a prevalent malignancy often diagnosed in advanced stages. Despite advancements in therapy, it retains a high mortality rate and significant recurrence risk. This study utilizes single-cell sequencing (scRNA-seq) to unravel HNSCC's complexity, identify therapeutic targets, and refine prognostic models.METHODSPseudotime trajectory and stemness analyses were performed on HNSCC tumor subpopulations, focusing on the C2 MALAT1+ Tumors subpopulation, which had the lowest CytoTRACE Score and represented the Lineage 2 endpoint in Slingshot analysis. The study examined programmed death and metabolic pathways in each subpopulation and developed a novel prognostic model using LASSO regression.RESULTSThe C2 MALAT1+ Tumors subpopulation exhibited reduced expression of programmed death pathways (e.g., Entotic cell death, Apoptosis, Pyroptosis) and metabolic pathways (e.g., Riboflavin metabolism, Glycolysis/Gluconeogenesis). Key transcription factors included LEF1, RFX3, CREM, MZF1, and ZNF202. Prognostic models based on the MALAT1 Tumors Risk Score (MTRS) revealed worse survival and higher tumor purity in the high MTRS group. Risk genes included ADM, RPL31, EIF5B, and TAF7. Additionally, activated CD4 memory T cells were enriched in the high MTRS group, which also showed greater sensitivity to Cisplatin, Docetaxel, and Paclitaxel.CONCLUSIONSScRNA-seq revealed the heterogeneity of HNSCC subpopulations, highlighting the unique features of the C2 MALAT1+ Tumors subpopulation. This study identified novel prognostic markers and therapeutic targets, offering insights into HNSCC progression, drug resistance, and potential treatments.

01 Apr 2025·Cell Death & Differentiation

Methionine-driven YTHDF1 expression facilitates bladder cancer progression by attenuating RIG-I-modulated immune responses and enhancing the eIF5B-PD-L1 axis

Article

Author: Chen, Wei ; Ma, Zifang ; Chen, Zhenhua ; Fu, Liangmin ; Yu, Anze ; Liu, Jinhui ; Yang, Rui ; Luo, Junhang ; Chen, Junxing ; Wang, Yinghan ; Zhou, Xinwei ; Zu, Xiongbing ; Yang, Taowei ; Feng, Wei ; Jing, Lanyu ; Hu, Jiao

AbstractThe impact of amino acids on tumor immunotherapy is gradually being uncovered. In this study, we screened various essential and non-essential amino acids and found that methionine enhances mRNA methylation and reduced the activation of Type I interferon pathway in bladder cancer. Through RNA sequencing, point mutations, MB49 mouse tumor models, and single-cell RNA sequencing, we demonstrated that high methionine levels elevate the expression of m6A reader YTHDF1, promoting the degradation of RIG-I, thereby inhibiting the RIG-I/MAVS-mediated IFN-I pathway and reducing the efficacy of tumor immunotherapy. Additionally, immunoprecipitation and mass spectrometry revealed that YTHDF1 binds to the eukaryotic translation initiation factor eIF5B, which acts on PD-L1 mRNA to enhance its translation and promote immune evasion. By intravesical administration of oncolytic bacteria VNP20009, we effectively depleted methionine locally, significantly prolonging mouse survival and enhancing immune cell infiltration and differentiation within tumors. Multiplex immunofluorescence assays in bladder cancer immunotherapy patients confirmed our findings. Our research elucidates two mechanisms by which methionine inhibits bladder cancer immunotherapy and proposes a targeted methionine depletion strategy that advances research while minimizing nutritional impact on patients.

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EIF5B

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