Skip to main content

AFF4

Developmental stage

Expressed in fetal heart, lung, brain and to a lower extent liver.

Function

Key component of the super elongation complex (SEC), a complex required 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 complex, AFF4 acts as a central scaffold that recruits other factors through direct interactions with ELL proteins (ELL, ELL2 or ELL3) and the P-TEFb complex. In case of infection by HIV-1 virus, the SEC complex is recruited by the viral Tat protein to stimulate viral gene expression.

Involvement in disease

A chromosomal aberration involving AFF4 is found in acute lymphoblastic leukemia (ALL). Insertion ins(5;11)(q31;q13q23) that forms a KMT2A/MLL1-AFF4 fusion protein.

CHOPS syndrome

CHOPS

A syndrome characterized by cognitive impairment, coarse facies, heart defects, obesity, pulmonary involvement, short stature, and skeletal dysplasia.

None

The disease is caused by variants affecting the gene represented in this entry.

Sequence similarities

Belongs to the AF4 family.

Tissue specificity

Ubiquitously expressed. Strongly expressed in heart, placenta, skeletal muscle, pancreas and to a lower extent in brain.

Cellular localization

  • Nucleus
  • Associates to transcriptionally active chromatin but not at snRNA genes.

Alternative names

  • AF4/FMR2 family member 4
  • ALL1-fused gene from chromosome 5q31 protein
  • Major CDK9 elongation factor-associated protein
  • Protein AF-5q31
  • MCEF
  • HSPC092
  • AFF4
  • AF5Q31

Target type

Proteins

Molecular weight

127459Da