Regulation of protein synthesis in eukaryotic cells by the guanine nucleotide exchange factor and chain initiation factor 2.
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.
Singh
L P
LP
Department of Biochemistry, University of Mississippi Medical Center, Jackson 39216-4500, USA.
Wahba
A J
AJ
D005057:Eukaryotic Cells / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006493:Heparin / Q000494:pharmacology; D006706:Homeostasis; D010084:Oxidation-Reduction; D010710:Phosphates / Q000494:pharmacology; D014176:Protein Biosynthesis; D011506:Proteins / Q000502:physiology*
D020662:Guanine Nucleotide Exchange Factors; D010710:Phosphates; D011506:Proteins; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D006493:Heparin