## **Core Concept**
Steroids act on cells by binding to specific intracellular receptors, which then interact with DNA to regulate gene expression. These receptors belong to the nuclear receptor superfamily and influence transcription by binding to specific DNA sequences known as hormone response elements (HREs). This interaction ultimately modulates the transcription of target genes.

## **Why the Correct Answer is Right**
The correct answer, **Zinc fingers**, is right because the nuclear receptors for steroids, once activated by their steroid ligands, translocate to the nucleus and bind to specific DNA sequences. This binding is facilitated by structures known as zinc fingers, which are crucial for the recognition and interaction with the major groove of the DNA double helix. Zinc fingers are protein domains that coordinate one or more zinc ions to help stabilize their fold, allowing them to recognize and bind to specific DNA sequences.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because while certain DNA-binding proteins interact with DNA through specific motifs, the term here is not specified, making it an unclear choice.
- **Option B:** This option is incorrect as it does not accurately describe the mechanism through which steroid receptors interact with DNA.
- **Option D:** This option is incorrect because it also does not accurately describe the mechanism through which steroid receptors interact with DNA.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the steroid hormone receptors, once activated, act as transcription factors themselves by directly interacting with DNA. This interaction is highly specific and is mediated by the zinc finger domains of these receptors. Understanding this mechanism is crucial for appreciating how steroid hormones exert their effects on gene expression and cellular function.

## **Correct Answer:** . Zinc fingers