{"title":"Regulation of protein synthesis in eukaryotic cells by the guanine nucleotide exchange factor and chain initiation factor 2.","authors":"L P Singh, A J Wahba","doi":"","DOIUrl":null,"url":null,"abstract":"<p><p>In eukaryotes, the guanine nucleotide exchange factor (eIF-2B) is a key protein in the control of polypeptide chain initiation. It catalyzes the exchange of chain initiation factor (eIF)-2-bound GDP for GTP and facilitates the formation of a ternary complex (eIF-2.GTP.Met-tRNAf). The activity of eIF-2B is inhibited indirectly by phosphorylation of the smallest subunit of eIF-2 which sequesters eIF-2B into an inactive eIF-2(alpha P).eIF-2B complex. On the other hand, eIF-2B activity may be regulated directly by covalent modification of its largest subunit with different kinases, such as casein kinase (CK)-I, CK-II and glycogen synthase kinase (GSK)-3. After stimulation of mammalian cells by insulin or growth factors, the allosteric activation of eIF-2B activity by sugar phosphates and inositol phosphates may also provide an important parameter in the regulation of protein synthesis.</p>","PeriodicalId":77373,"journal":{"name":"SAAS bulletin, biochemistry and biotechnology","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"1996-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"SAAS bulletin, biochemistry and biotechnology","FirstCategoryId":"1085","ListUrlMain":"","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
In eukaryotes, the guanine nucleotide exchange factor (eIF-2B) is a key protein in the control of polypeptide chain initiation. It catalyzes the exchange of chain initiation factor (eIF)-2-bound GDP for GTP and facilitates the formation of a ternary complex (eIF-2.GTP.Met-tRNAf). The activity of eIF-2B is inhibited indirectly by phosphorylation of the smallest subunit of eIF-2 which sequesters eIF-2B into an inactive eIF-2(alpha P).eIF-2B complex. On the other hand, eIF-2B activity may be regulated directly by covalent modification of its largest subunit with different kinases, such as casein kinase (CK)-I, CK-II and glycogen synthase kinase (GSK)-3. After stimulation of mammalian cells by insulin or growth factors, the allosteric activation of eIF-2B activity by sugar phosphates and inositol phosphates may also provide an important parameter in the regulation of protein synthesis.