Steroid hormones, such as cortisol and testosterone, are lipid-soluble molecules derived from cholesterol. Due to their lipophilic nature, they can easily diffuse across the plasma membrane of target cells. Once inside the cell, they interact with specific intracellular receptors, which are part of the nuclear receptor superfamily. The interaction between steroid hormones and their target cell receptors leads to the activation of specific signaling pathways, ultimately resulting in changes in gene expression and cellular function.1. Hormone transport: Steroid hormones are transported in the bloodstream, bound to specific carrier proteins such as sex hormone-binding globulin SHBG for testosterone and cortisol-binding globulin CBG for cortisol. These carrier proteins protect the hormones from degradation and help maintain their concentrations in the blood.2. Hormone entry into the target cell: As steroid hormones are lipophilic, they can easily diffuse across the lipid bilayer of the plasma membrane of target cells.3. Interaction with intracellular receptors: Once inside the cell, steroid hormones bind to their specific intracellular receptors, which are usually located in the cytoplasm or nucleus. These receptors are part of the nuclear receptor superfamily and consist of a DNA-binding domain, a ligand-binding domain, and a transcription activation domain.4. Receptor activation and dimerization: Upon binding to the hormone, the receptor undergoes a conformational change, which leads to its activation. Activated receptors can form homodimers two identical receptors or heterodimers two different receptors in the case of some steroid hormone receptors.5. Nuclear translocation: The hormone-receptor complex then translocates to the nucleus, where it binds to specific DNA sequences called hormone response elements HREs located in the promoter regions of target genes.6. Regulation of gene transcription: The binding of the hormone-receptor complex to HREs leads to the recruitment of coactivators or corepressors, which modulate the transcription of target genes. Coactivators enhance gene transcription, while corepressors inhibit it. This process ultimately results in the upregulation or downregulation of specific target genes, leading to changes in protein synthesis and cellular function.7. Termination of signaling: The signaling pathway is terminated when the hormone is metabolized or dissociates from the receptor. The receptor can then be recycled or degraded.In summary, steroid hormones such as cortisol and testosterone interact with their target cell receptors by diffusing across the plasma membrane and binding to specific intracellular receptors. This binding leads to receptor activation, dimerization, nuclear translocation, and regulation of gene transcription. The resulting changes in gene expression and protein synthesis ultimately lead to alterations in cellular function.