AF4/FMR2 family member 4 (AFF4)

Key part of the super elongation complex (SEC), a complex needed to increase the catalytic rate of RNA polymerase II transcription by suppressing transient pausing by the polymerase at multiple sites along the DNA. In the SEC complicated, AFF4 acts as a central scaffold that recruits other variables through direct connections with ELL proteins (ELL, ELL2 or ELL3) and the P-TEFb complicated.

In the event of infection by HIV-1 virus, the SEC complex is recruited by the viral Tat protein to stimulate viral gene expression. .