Steroid and thyroid hormones are hydrophobic and diffuse from their binding proteins in the plasma, across the plasma membrane to intracellular localized receptors.
These receptors are proteins located in the cytosol and in the nucleus. They belong to the nuclear superfamily of receptors that include receptors for Vitamin A, Vitamin D and other hydrophobic metabolites. Receptors for steroid hormones (Type I receptors) are typically located in the cytosol, associated to Heat Shock Proteins (HSP).
When the hormone diffuse into the cytosol, binds to these receptors, releasing the HSP, and the resultant complex of steroid and receptor travels to the nucleus.
In the nucleus, the Hormone-receptor complex recognize and bind to specific sequences of nucleotides in the DNA, called Hormone Response Elements (HRE).
This interaction Hormone-Receptor-HRE modify the expression of the associated gen, regulating the production of mRNA for specific proteins.
Recommended videos availables in You Tube:
1.- A short video explaining the basic of the cellular mechanism of steroid hormones action:
2.- A very detailed lecture about the Nuclear receptors family: