<p> Proteins of this entry, found in the cyanobacteria, are the global nitrogen regulator NtcA. This DNA-binding transcriptional regulator is required for expressing many different ammonia-repressible genes. The consensus NtcA-binding site is GTA(N8)TAC [<cite idref="PUB00053576"/>, <cite idref="PUB00053577"/>].</p>