The gene consists of 20 exons that span approximately 43 kb of genomic DNA in the centromere-to-telomere orientation. The translation initiation codon and stop codon are located to exon 2 and exon 20, respectively.

Two isoforms of BRD4 have been reported. The "BRD4 long isoform" corresponds to the ordinary full length transcript while the "BRD4 short isoform" corresponds to an alternative splicing variant lacking exons 12-20. The "BRD4 long variant" encodes a 6.0 kb transcript and the "BRD4 short variant" encodes a 4.4 kb transcript.

BRD4 belongs to the BET subgroup of the bromodomain superfamily and contains 2 bromodomains and a conserved ET-domain.
The open reading frame encodes a 1362 amino acid protein with a molecular weight of 200 kDa.

Northen blot analysis has shown an ubiquitous normal expression of both BRD4 isoforms.

Nuclear.

A striking feature of BRD4 is its association with euchromatic regions of mitotic chromosomes. By this association, the protein exerts its function as regulator of cell cycle progression from G2 to M but also in the G1 to S transition. It has also been suggested that the association of BRD4 to chromatin is important for the transmission of a transcriptional memory during cell division.

The vast majority of reported 19p breakpoints were assigned to band 19p13, the exception being the cytogenetic interpretation of a 19q13 breakpoint reported once. The reported breakpoints on chromosome 15 have varied (15q11-q15).