Receptors (from lat. recipere = to take up or receive) belong on a molecular level to a family of cellular proteins or protein complexes whose task it is to mediate the effects of the body's own signal substances. Such receptors are also used, for example, by pharmaceuticals which have an agonistic (receptor activating) or an antagonistic (receptor inhibiting) effect.
In principle, receptors have 2 functions:
Receptors generally bind the signalling substance according to a lock-and-key principle
Receptors initiate a signal via receptor-specific transduction pathways that stimulates or inhibits cellular functions.
Receptors either protrude from the surface of a biomembrane (membrane-bound receptors) or are located in the interior of the cell (intracellular receptors) where they trigger specific signalling processes after activation.
On the molecular level, a distinction is thus made between:
membrane-bound receptors
and
intracellular receptors (steroid receptors, receptors for vitamin D, thyroid hormones, retinoid receptors)
S. a. receptor (internal medicine)