Gene expression is highly regulated by complex protein translation systems. Expression within the eukaryotic cell is especially complicated, involving the mature mRNA, the ribosomal subunits and other protein factors. Furthermore, each component has to interact in a specific function i.e. the small ribosomal subunit has to recognise a start codon, and the large ribosomal subunit has to be recruited before translation can be initiated (Wagner et al 2002). One such protein is the eukaryotic translation initiation factor 4G (eIF4G), which participates in the recruiting of the small 40S ribosomal subunit and in scanning along the 5' UTR of the mRNA to the translation start codon. Other regulatory proteins which interact in tandem with the eIF4G include the 5'-cap-binding protein eIF4E and RNA helicase eIF4A (Aravind and Koonin, 2000; Korneeva et al. 2001; Yamamoto et al. 2005).
This study used a comparative method based on the MIF4G-like protein from the zebrafish. The protein was studied for its functional, structural and evolutionary properties. Preliminary information provided by the crystal structure of the protein revealed it to be similar to the middle domain of the eIF4G protein, hence described as "MIF4G-like protein". To improve the understanding of the properties of this protein found in humans, computational tools were used to predict the structure, function and evolutionary history of MIF4G. The eIF4G domain consists of three domains of which MIF4G is the middle domain. eIF4G is also made up of three HEAT domains of which HEAT-1 corresponds to MIF4G. It is known that one of the functions of the eIF4G domain is to bind to eIF4A during translation initiation (Andrade et al 2001). This study hopes to further the knowledge about evolution, function and structure of the MIF4G domain within eIF4G.
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