6o81
From Proteopedia
Electron cryo-microscopy of the eukaryotic translation initiation factor 2B bound to translation initiation factor 2 from Homo sapiens
Structural highlights
Disease[EI2BD_HUMAN] Juvenile or adult CACH syndrome;Congenital or early infantile CACH syndrome;Cree leukoencephalopathy;Late infantile CACH syndrome;Ovarioleukodystrophy. The disease is caused by mutations affecting the gene represented in this entry. [IF2G_HUMAN] The disease is caused by mutations affecting the gene represented in this entry. [EI2BB_HUMAN] Cree leukoencephalopathy;Juvenile or adult CACH syndrome;Congenital or early infantile CACH syndrome;Late infantile CACH syndrome;Ovarioleukodystrophy. The disease is caused by mutations affecting the gene represented in this entry. [EI2BE_HUMAN] Defects in EIF2B5 are a cause of leukodystrophy with vanishing white matter (VWM) [MIM:603896]. VWM is a leukodystrophy that occurs mainly in children. Neurological signs include progressive cerebellar ataxia, spasticity, inconstant optic atrophy and relatively preserved mental abilities. The disease is chronic-progressive with, in most individuals, additional episodes of rapid deterioration following febrile infections or minor head trauma. While childhood onset is the most common form of the disorder, some severe forms are apparent at birth. A severe, early-onset form seen among the Cree and Chippewayan populations of Quebec and Manitoba is called Cree leukoencephalopathy. Milder forms may not become evident until adolescence or adulthood. Some females with milder forms of the disease who survive to adolescence exhibit ovarian dysfunction. This variant of the disorder is called ovarioleukodystrophy.[1] [2] [3] [4] [5] [6] [EI2BA_HUMAN] Cree leukoencephalopathy;Late infantile CACH syndrome;Ovarioleukodystrophy. The disease is caused by mutations affecting the gene represented in this entry. [EI2BG_HUMAN] Juvenile or adult CACH syndrome;Congenital or early infantile CACH syndrome;Cree leukoencephalopathy;Late infantile CACH syndrome;Ovarioleukodystrophy. The disease is caused by mutations affecting the gene represented in this entry. Function[IF2A_HUMAN] Functions in the early steps of protein synthesis by forming a ternary complex with GTP and initiator tRNA. This complex binds to a 40S ribosomal subunit, followed by mRNA binding to form a 43S preinitiation complex. Junction of the 60S ribosomal subunit to form the 80S initiation complex is preceded by hydrolysis of the GTP bound to eIF-2 and release of an eIF-2-GDP binary complex. In order for eIF-2 to recycle and catalyze another round of initiation, the GDP bound to eIF-2 must exchange with GTP by way of a reaction catalyzed by eIF-2B. [EI2BD_HUMAN] Catalyzes the exchange of eukaryotic initiation factor 2-bound GDP for GTP. [IF2G_HUMAN] As a subunit of eukaryotic initiation factor 2 (eIF2), involved in the early steps of protein synthesis. In the presence of GTP, eIF2 forms a ternary complex with initiator tRNA Met-tRNAi and then recruits the 40S ribosomal complex, a step that determines the rate of protein translation. This step is followed by mRNA binding to form the 43S pre-initiation complex. Junction of the 60S ribosomal subunit to form the 80S initiation complex is preceded by hydrolysis of the GTP bound to eIF2 and release of an eIF2-GDP binary complex. In order for eIF2 to recycle and catalyze another round of initiation, the GDP bound to eIF2 must exchange with GTP by way of a reaction catalyzed by eIF2B (By similarity). Along with its paralog on chromosome Y, may contribute to spermatogenesis up to the round spermatid stage (By similarity).[UniProtKB:Q9Z0N1] [EI2BB_HUMAN] Catalyzes the exchange of eukaryotic initiation factor 2-bound GDP for GTP. [EI2BE_HUMAN] Catalyzes the exchange of eukaryotic initiation factor 2-bound GDP for GTP. [EI2BA_HUMAN] Catalyzes the exchange of eukaryotic initiation factor 2-bound GDP for GTP. [EI2BG_HUMAN] Catalyzes the exchange of eukaryotic initiation factor 2-bound GDP for GTP. Publication Abstract from PubMedThe integrated stress response (ISR) tunes the rate of protein synthesis. Control is exerted by phosphorylation of the general translation initiation factor eIF2. eIF2 is a guanosine triphosphatase that becomes activated by eIF2B, a two-fold symmetric and heterodecameric complex that functions as eIF2's dedicated nucleotide exchange factor. Phosphorylation converts eIF2 from a substrate into an inhibitor of eIF2B. We report cryo-electron microscopy structures of eIF2 bound to eIF2B in the dephosphorylated state. The structures reveal that the eIF2B decamer is a static platform upon which one or two flexible eIF2 trimers bind and align with eIF2B's bipartite catalytic centers to catalyze nucleotide exchange. Phosphorylation refolds eIF2alpha, allowing it to contact eIF2B at a different interface and, we surmise, thereby sequestering it into a nonproductive complex. eIF2B-catalyzed nucleotide exchange and phosphoregulation by the integrated stress response.,Kenner LR, Anand AA, Nguyen HC, Myasnikov AG, Klose CJ, McGeever LA, Tsai JC, Miller-Vedam LE, Walter P, Frost A Science. 2019 May 3;364(6439):491-495. doi: 10.1126/science.aaw2922. PMID:31048491[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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