What type of receptor protein is located inside the cell and is involved in cell signaling?

The type of receptor protein located inside the cell and involved in cell signaling is an intracellular receptor protein. These receptors are typically found in the cytoplasm or nucleus of target cells and function by binding to specific ligands, such as steroid hormones, that can cross the cell membrane. When a ligand binds to an intracellular receptor, it often results in a conformational change that allows the receptor-ligand complex to interact with DNA, influencing gene expression and ultimately affecting cellular responses.

In contrast, membrane receptors, extracellular receptors, and transmembrane receptors are found on the cell surface and are designed to bind to signaling molecules outside the cell, initiating a variety of intracellular signaling cascades without interacting directly with DNA. The intracellular receptor's ability to directly influence gene expression is a distinctive and critical feature of this receptor class in cell signaling processes.