A molecule inside or on the surface of a cell that binds to a specific substance and causes a specific physiologic effect in the cell.

A protein located on the cell surface, or in the cytoplasm, that binds to a specific signaling factor, such as a hormone, antigen, or neurotransmitter, causing a conformational and functional change in the receptor molecule. The ligand-bound receptor then alters its interaction with target molecules, which leads to changes in cellular physiology through modification of the activity of one or more signal transduction pathways.

Diverse family of binding proteins which mediate the biological effects of regulatory molecules such as hormones; many are intrinsic membrane proteins; others (such as the steroid receptors) are cytoplasmic carriers; postcoordinate this term with specific ligand terms.

Structures on the outside of a cell membrane that permit attachment of specific chemicals.

Receptor, molecule, generally a protein, that receives signals for a cell. Small molecules, such as hormones outside the cell or second messengers inside the cell, bind tightly and specifically to their receptors. Binding is a critical element in effecting a cellular response to a signal and is...