The following eukaryotic proteins are evolutionary related and are thought to be involved in transcriptional regulation.

• Vertebrate protein TSC-22 [1]. This protein of 144 residues seems to act a transcriptional regulator on C-type natriuretic peptide (CNP) promoter.
• Mammalian protein DIP (DSIP-immunoreactive peptide) [2], a protein of 77 amino acids, whose function is not yet known.
• Drosophila protein bunched [3] (gene bun) (also known as shortsighted), a probable transcription factor required for peripheral nervous system morphogenesis, eye development and oogenesis.
• Caenorhabditis elegans hypothetical protein T18D3.7.

These proteins are highly similar in a region of about 50 residues that include a conserved leucine-zipper domain most probably involved in homo- or hetero-dimerization. As a signature pattern we selected a highly conserved stretch of residues that is located just in front of the leucine zipper.