What mechanism binds to receptors within the target cell nucleus and influences cell activity by acting on DNA?

Steroid hormones interact with receptors located in the target cell's nucleus, which allows them to directly influence cell activity at the genetic level. These hormones are lipid-soluble, enabling them to easily cross the cell membrane and bind to specific intracellular receptors. Once bound, the hormone-receptor complex translocates to the nucleus, where it can bind to specific regions of DNA and regulate the transcription of certain genes. This mechanism leads to changes in protein synthesis and ultimately alters the function and behavior of the target cell.

In contrast, growth factors typically bind to surface receptors and initiate signaling cascades without directly engaging DNA. Nonsteroid hormones often rely on secondary messengers to convey their signals, which occurs outside the nucleus and does not involve direct binding to DNA. Neurotransmitters also operate primarily at synaptic junctions and interact with receptors on the cell surface rather than entering the nucleus to affect genetic transcription. The defining feature of steroid hormones is their ability to modify gene expression directly within the nucleus, making them the correct answer.