Recognizes and binds the palindromic sequence 5'-TTGGCNNNNNGCCAA-3' present in viral and cellular promoters and in the origin of replication of adenovirus type 2. These proteins are individually capable of activating transcription and replication.
Coexpression of NFI-B3 with other isoforms of the NFI-B, -C, and -X family, however, led to a strong reduction of transcriptional activation compared with the expression of these factors alone. NFI-B3 apparently forms heterodimers with other NFI proteins thereby interfering with their function.