Final answer:
Steroid hormones primarily use intracellular nuclear receptors to regulate gene expression within a target cell. These hormones can cross cellular membranes due to their lipophilic properties, allowing them to directly influence mRNA synthesis and protein production.
Step-by-step explanation:
Steroid hormones generally employ nuclear receptors. These receptors are intracellular and once the steroid hormone passes through the plasma membrane, the hormone binds to these nuclear receptors located either in the cytoplasm or directly in the nucleus. The hormone-receptor complex then acts as a transcription regulator influencing gene expression by affecting the synthesis of mRNA and consequently altering the production of proteins within the cell. This is in contrast to other hormone receptors such as G-protein-coupled receptors, ion-channel-coupled receptors, and enzyme-coupled receptors, which are typically located on the cell surface and are used by peptide and amino acid-derived hormones.
Lipid-derived hormones like steroids easily diffuse through the lipid bilayer because of their hydrophobic nature, allowing them to access these intracellular nuclear receptors, which then directly initiate transcription and translation to produce a functional protein response within the cell.