What role do receptor proteins play in cells?

Receptor proteins play a crucial role in cellular communication and signaling by sensing and reacting to specific molecules, such as hormones, neurotransmitters, or other signaling molecules. When these molecules bind to their respective receptor proteins, it triggers a series of biochemical events within the cell, leading to a response. This process is essential for coordinating various physiological processes, including growth, immune response, and homeostasis. The specificity of receptor proteins allows cells to respond to particular signals, which is fundamental in maintaining the integrity and function of biological systems.

The other options do not accurately describe the primary function of receptor proteins. Transporting nutrients across membranes is typically the role of transport proteins. Providing structural support to cells is the function of structural proteins, such as collagen or cytoskeletal proteins. Assisting in DNA replication involves enzymes like DNA polymerases, which are not related to receptor functions. Thus, option C correctly identifies the specific role of receptor proteins in the context of cellular functions.