FIG. 8.

Schematic representation of the regulation of HIV translation by PKR and the contribution of host and viral factors. The viral TAR RNA contributes to PKR activation by inducing its phosphorylation, which in turn phosphorylates eIF2α and consequently inhibits HIV translation. During HIV replication, the cellular proteins TRBP and ADAR1 prevent or inhibit PKR phosphorylation, whereas the viral protein Tat prevents eIF2α phosphorylation. All three proteins contribute to increased HIV translation.