How many DNA-binding transcription factors are estimated in the human genome?

How many DNA-binding transcription factors are estimated in the human genome?

• A. Approximately 200 to 300.
• B. Approximately 1,600 to 2,000.
• C. Approximately 10,000 to 12,000.
• D. Approximately 50 to 100.

Answer: (B)

DNA-binding transcription factors are proteins that bind specific DNA sequences to control gene transcription. In humans, the number of genes encoding these sequence-specific DNA-binding factors is about 1,600 to 2,000. This range reflects the diversity of families—such as zinc finger, homeodomain, basic helix–loop–helix, and leucine zipper proteins—and the need for many regulators to drive precise, tissue- and development-specific gene expression through combinatorial interactions with cofactors and signaling cues. Large-scale genome analyses classify these proteins by their DNA-binding domains, leading to this broad, yet still approximate, count. The other options underestimate or overestimate the scope: too few wouldn’t support the complex regulatory networks, while numbers on the order of tens of thousands would exceed the total number of protein-coding genes and would include many non–DNA-binding regulators.

DNA-binding transcription factors are proteins that bind specific DNA sequences to control gene transcription. In humans, the number of genes encoding these sequence-specific DNA-binding factors is about 1,600 to 2,000. This range reflects the diversity of families—such as zinc finger, homeodomain, basic helix–loop–helix, and leucine zipper proteins—and the need for many regulators to drive precise, tissue- and development-specific gene expression through combinatorial interactions with cofactors and signaling cues. Large-scale genome analyses classify these proteins by their DNA-binding domains, leading to this broad, yet still approximate, count. The other options underestimate or overestimate the scope: too few wouldn’t support the complex regulatory networks, while numbers on the order of tens of thousands would exceed the total number of protein-coding genes and would include many non–DNA-binding regulators.