Naturally occurring receptor functions

Hu J, Spiegel AM (2003) Naturally occurring mutations of the extracellular Ca2+-sensing receptor implications for its structure and function. Trends Endocrinol Metab 14 282-288... 

Melanocortins. Figure 1 Shows the melanocortin receptors, function and naturally occurring peptide sequences that activate them. 

Many psychoactive drugs act to alter neurotransmitter functions either through effects on their synthesis, metabolism or reuptake or by directly affecting the receptors for naturally occurring compounds. For example, drugs such as prozac increase serotoniner-gic activity by selective serotonin reuptake inhibition (SSRI). 

Koyano, S., Kurose, K., Saito, Y., et al. (2004) Functional characterization of four naturally occurring variants of human pregnane X receptor (PXR) one variant causes dramatic loss of both DNA binding activity and the transactivation of the CYP3A4 promoter/enhancer region. Drug Metab. Dispos. 32, 149-154. 

The discovery of a multitude of naturally occurring, bioactive peptides has generated a rich source of pharmacophores from which medicinal chemists are developing new useful therapeutic drugs. After binding to an enzyme, or a membrane receptor, peptide-based inhibitors, neurotransmitters, immunomodulators, and hormones influence cell-to-cell communications and control a variety of vital functions such as metabolism, immune defense, digestion, respiration, sensitivity to pain, reproduction, and behavior. 

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