Sites of Expression

Although leukocytes continue to be the major site of expression of chemokine receptors, several studies have recently demonstrated chemokine receptor expression on neurons in the CNS. 

The expression of a significant gut wall first-pass extraction ratio has several implications for affected drugs. First, oral bioavailability is lower than would be expected from the extent of absorption and the hepatic first-pass extraction. Second, the variability in expression of gut wall metabolic enzymes and transporters can lead to significant variability in gut wall first-pass extraction and thus oral bioavailability. Finally, the site of expression of these enzymes and transporters (i.e., the villus tip) brings them into contact with potentially co-administered drugs or dietary constituents, which could be inhibitors or inducers. Thus, there is the potential for drug-drug interactions at the level of the gut wall. 

The a7-containing nAChRs were discovered earlier than the other neuronal nAChRs and are of enormous interest because of their unique properties (e.g., high permeability to Ca++) and sites of expression. 

Sites of expression Ocular and extraocular photoreceptors Retinal pigment epithelium and Muller cells Ocular and extraocular photoreceptors... 

Yaar R, Lamperti ED, Toselli PA, Ravid K (2002) Activity of the A3 adenosine receptor gene promoter in transgenic mice characterization of previously unidentified sites of expression. FEBS Lett 532(3) 267-272... 

Serotonin (5-hydroxytryptamine [5-HT]) produces its effects through a variety of membrane-bound receptors, located in the central and peripheral nervous systems and in non-neuronal tissues in the gastrointestinal tract, cardiovascular system, and blood. The knowledge of the anatomical localization of the receptors is an important step forward for the understanding of their function. Several techniques allow the microscopic visualization of the sites of expression of these receptors in the tissues. In this review, we will attempt to summarize the available information on the neuroanatomical organization of each one of the 5-HT receptor subtypes. 

When the sites of expression of 5-HT1F receptor mRNA in guinea pig brain are compared to the [3H]sumatriptan-binding sites insensitive to 5-CT, a clear correspondence between both distributions is observed, an indication that 5-HT1F receptors are localized in the cell bodies and/or dendrites (see Fig. 5). 

SULT Isoform Probe Substrates Known Drug Substrates Major Sites of Expression... 

Nicotinic receptors are made up of five subunits, arranged symmetrically around a central pore. They share similarities with GABAa receptors, glycine receptors and type 3 serotonin receptors. They are broadly classified into two subtypes based on their primary sites of expression, namely muscle type and neuronal type to date 17 uAChR subunits have been identified. Of these 2-7 and /S2-4 have been cloned in humans the remaining genes have been identified in chick and rat genomes. 

Kullmann DM, Siegelbaum SA (1995) The site of expression of NMDA receptor-dependent LTP New fuel for an old fire. Neui on 15 997-1002. 

Kusakabe, M., I. Nakamura and G. Young. 11/3-Hydroxysteroid dehydrogenase complementary deoxyribonucleic acid in rainbow trout cloning, sites of expression, and seasonal changes in gonads. Endocrinology 144 2534-2545, 2003. 

The numerical diversity of Na channel genes and their variable expression patterns increase the probabihty that the anticipated channel subunit mutations will generate multiple CNS excitability profiles finked to distinct clinical seizure types. Each of these selective excitability increases in specific axonal pathways may act to synchronize large neuronal populations by synaptic or non-synaptic mechanisms. This review considers the anatomical aspects of Na channel involvement in epileptogenesis, namely, how the site of expression of the Na channel gene, both within the neuron and within specific brain pathways, acts as an important phenotypic determinant of the disorder. 

Each of the 57 human P450s will be covered here. Clearly much more information is available about some than others. Points to be covered with each, when possible, include sites of expression and relative abundance, polymorphism and inducibility, substrates and reactions, knowledge of important residues and active site characteristics, inhibitors, and clinical issues. 

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