Final answer:
Steroid hormone-nuclear receptor complexes bind to DNA regulatory elements through zinc-finger domains and function as dimers, with a C-terminal ligand-binding domain. The receptors bind to hormone response elements, facilitating the regulation of gene transcription. Therefore, options B, C, and D are incorrect, and only option A describes a characteristic of these complexes accurately.
Step-by-step explanation:
Steroid hormone-nuclear receptor complexes have a multitude of functions and characteristics. These complexes are typically formed when a steroid hormone binds to its receptor protein, either in the cytoplasm or the nucleus. However, to exert their regulatory effects on gene transcription, these complexes must bind to DNA regulatory elements, such as promoters or enhancers. They do not do so in their monomeric form, as option B suggests, but rather as dimers, which is a key requirement for DNA binding.
The zinc-finger domain is crucial for the DNA binding capability of these receptors, and it typically involves the presence of zinc atoms that are coordinated with cysteine residues to maintain the structural integrity of the domain. These zinc-finger motifs facilitate the binding of the complex to specific DNA sequences known as response elements. Therefore, the statement A, which mentions two adjacent zinc fingers in their DNA binding domain, is accurate for many such nuclear receptors.
The ligand-binding domain, which is responsible for binding the steroid hormone, is actually located on the C-terminal rather than the N-terminal, contradicting option C. Lastly, steroid hormone-nuclear receptor complexes most certainly interact with DNA, so option D is incorrect.