Translation initiation factor 4A a prototype memb

Authors: Narendra Tuteja Ajay Amar Vashisht Renu Tuteja

Publish Date: 2008/06/15

Volume: 14, Issue: 1-2, Pages: 101-

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Abstract

DEADbox proteins are characterized by nine conserved helicase motifs Several different DEADbox proteins are found in eukaryotes whereas prokaryotes have small number of these proteins They play important roles in almost all kinds of RNA metabolism including roles in remodeling ribonuclear protein complexes These proteins are usually very specific and cannot mutually be replaced Many of these DEADbox proteins but not all have been shown to have RNAdependent ATPase and ATPdependent RNA helicase activities Many of them have also been shown to contain DNA unwinding activities Translation initiation factor 4A is the prototype of the DEADbox family of proteins Actually the DEADbox protein family was discovered on the basis of conserved sequence motifs of eIF4A Motif II or Walker B motif has the amino acids DEAD AspGluAlaAsp which gave the name to the family In general the eIF4A is considered as a helicase that locally melts the secondary structures and makes the RNA accessible to nucleases It is part of the capbinding complex eIF4F but is also found to be present in a free form The biochemical activities of eIF4A are reported to be upregulated by eIF4B eIF4H and eIF4G It has been proposed that eIF4A helps to unwind secondary structures in the 5′untranslated region which are inhibitory for protein synthesis In plants it has been shown to play a unique role in abiotic stress tolerance which suggests a new pathway to engineer to increase the crop production under the stress conditions

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