Receptors

Receptors are vital to cell communication in various different forms of signalling - paracrine, synaptic, endocrine etc.They are proteins that bind specific signal molecules to trigger a response from the target cell.Receptors can be transmembrane proteins found on the extracellular surface of target cells, or they can be found inside the cell. In the case of intra-cellular receptors the signalling molecule must enter the cell to activate the receptor.