What kind of protein is a transmembrane receptor?

Transmembrane receptors are integral membrane proteins that span the lipid bilayer of the cell membrane. They play a crucial role in cell signaling by binding to specific extracellular ligands, such as hormones or neurotransmitters, which then trigger a response within the cell.

Choosing cell signaling receptor protein in the membrane accurately reflects the function of transmembrane receptors. These proteins facilitate communication between the extracellular environment and the intracellular space, responding to chemical signals and activating various intracellular signaling pathways. This process is vital for numerous cellular functions, including growth, immune responses, and homeostasis.

The other options do not accurately describe transmembrane receptors. Cytoplasmic receptor proteins are located within the cell and do not span the membrane. Extracellular ligands refer to the signaling molecules themselves rather than the receptors that bind them. Nuclear receptor proteins, like cytoplasmic ones, function within the cell but typically respond to ligands that diffuse through the membrane and bind to receptors in the nucleus or cytoplasm, rather than being embedded in the membrane.