Expression of initiation factor genes in mammalian cells.
This review focuses on how cells establish the levels of initiation factors, within the broader context of determining levels of the translational machinery. Most initiation factor polypeptides are moderately abundant proteins with concentrations approaching those of ribosomes. eIF4A and eIF5A are more abundant than ribosomes, whereas eIF4F alpha and eIF2B are considerably less abundant than the other factors. The cloning of cDNAs generates hybridization probes for monitoring the levels and activities of factor mRNAs, and the cloning of their genes is just beginning to provide insight into promoter structures and regulation. Initiation factor gene expression appears to be coordinately regulated in many cases, and preferential synthesis is seen in mitogen-activated T-cells. The gene for eIF2 alpha has been best characterized, and mechanisms that provide for the coordinated synthesis of eIF2 subunits are emerging. Recombinant DNA methods also allow investigators to manipulate the levels of expression of specific factor genes by overexpression or antisense repression. Such approaches provide a means to investigate in vivo the mechanisms of action of the initiation factors and their roles in regulating translation rates.
Hershey
J W
JW
Department of Biological Chemistry, School of Medicine, University of California, Davis 95616.
D000818:Animals; D002477:Cells / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D008322:Mammals; D010448:Peptide Initiation Factors / Q000235:genetics*
D010448:Peptide Initiation Factors