Eukaryotic initiation factor

EIF4A ( eukaryotic initiation factor 4A) refers to a group of proteins that are involved in the translation of mRNA into proteins. They are among the initiation factors. Via the existing amount of eIF4A translation and thus the protein synthesis in the cell is controlled.

The eIF4A act as helicase for unwinding of the mRNA to be translated, and as ATPase. The energy required for this process is obtained from the hydrolysis of ATP. By unwinding the ribosomes, the addition is made possible to the mRNA.

However, the translation is not always highly dependent on the activity of eIF4A, eIF4A as needed for the typical eukaryotic mRNA 5'- cap structure to the formation of the initiation complex. A cap- independent initiation mechanism used by an mRNA (e.g., by an internal ribosome entry site, IRES), then the eIF4A binding to IRES not the critical step to bind to the ribosome and consequently the translational no longer the initiation complex regulated. This cap-independent translation is from a few cellular genes (such as the oncogene c-myc or of ornithine decarboxylase ), and some viruses (e.g., hepatitis C virus or picornaviruses such as the poliomyelitis virus ) is used. In addition, viral proteins of poliovirus are able to cleave the eIF4G thereby to prevent the translation of cellular mRNAs.

An inhibitor of the activity of eIF4A is the coral - steroid Hippuristanol.