Drug-protein interactions, plasma membrane

The inhibition of tumor growth by unsaturated ketonucleosides could, therefore, be due to selective alkylation of the SH groups of key proteins that control cell division. Because the plasma membrane is the first barrier encountered by the drugs, it seems important to consider the interaction of unsaturated ketonucleosides with this cellular structure.76... 

This definition has been the basis for an enormous body of scientific investigation into the function and regulation of receptors and mechanisms of drug action. However, final proof of the existence of receptors did not occur until relatively recent applications of modern biochemistry and molecular biology to purify, sequence, clone, and express pure receptor proteins. This lack of proof notwithstanding, the therapeutic basis of many modern, and not so modern, drugs resides in their specific interactions with receptor molecules located in the plasma membrane or cytosol of target cells. In fact, these specific interactions have provided the experimental basis for their discovery and development. 

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