Related Experiment Video
Updated: Jul 12, 2026

Xenopus laevis as a Model to Identify Translation Impairment
Published on: September 27, 2015
Defect in the GTPase activating protein (GAP) function of eIF5 causes repression of GCN4 translation
Charles Antony A1, Pankaj V Alone1
1School of Biological Sciences, National Institute of Science Education and Research Bhubaneswar, Constituent Institutes of Homi Bhabha National Institute (HBNI), P.O Jatni, Khurda 752050 India.
Abstract:
In eukaryotes, the eIF5 protein plays an important role in translation start site selection by providing the GAP (GTPase activating protein) function. However, in yeast translation initiation fidelity defective eIF5G31R mutant causes preferential utilization of UUG as initiation codon and is termed as Suppressor of initiation codon (Sui-) phenotype due to its hyper GTPase activity. The eIF5G31R mutant dominantly represses GCN4 expression and confers sensitivity to 3-Amino-1,2,4-Trizole (3AT) induced starvation. The down-regulation of the GCN4 expression (Gcn- phenotype) in the eIF5G31R mutant was not because of leaky scanning defects; rather was due to the utilization of upUUG initiation codons at the 5' regulatory region present between uORF1 and the main GCN4 ORF.
Related Concept Videos
GTPases and their Regulation
Large G-proteins, also known...
Eukaryotic Transcription Inhibitors
Eukaryotic transcription inhibitors usually contain two distinct domains, a DNA...
Rab Proteins
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
GTPases and their Regulation
Large G-proteins, also known...
Small GTPases - Ras and Rho
Three regulatory proteins control their activity:
Activation and Inactivation of G Proteins

