Receptor-transducer

As early as 1848, it had been suggested that sensory receptors transduce only one sensation, independent of the manner of stimulation. Behavioral experiments tend to support this theory. In 1919, Renqvist proposed that the initial reaction of taste stimulation takes place on the surface of the taste-cell membrane. The taste surfaces were regarded as colloidal dispersions in which the protoplasmic, sensory particles and their components were suspended in the liquor or solution to be tested. The taste sensation would then be due to adsorption of the substances in the solution, and equal degrees of sensation would correspond to adsorption of equal amounts. Therefore, the rate of adsorption of taste stimulants would be proportional to the total substances adsorbed. The phenomenon of taste differences between isomers was partly explained by the assumption that the mechanism of taste involves a three-dimensional arrangement for example, a layer of fatty acid floating on water would have its carboxylic groups anchored in the water whereas the long, hydrocarbon ends would project upwards. 

Signal —> Receptor — Transducer — Effector — Response, upstream — downstream... 

Antonsson and Marinou 2000 Adams and Cory, 1998). Stress may also cause inaease, nitric oxide (NO), or reactive oxygen species (ROS) production which, in turn, triggers release of apoptotic proteins from the intermemhrane space (Kroemer and Reed, 2000 Vieira et at, 2000). Release of these proteins from mitochondria are required for stress induced killing hut are, with a few exceptions (Bergmann et al, 1994, Schulze- Osthoff et al, 1993), dispensible for CD95 and TNF-receptor transduced apoptosis. These other death processes require FADD and caspase-8 to be recruited into the death receptor complexes and cannot be blocked by Bcl-2 (Krammer, 2000 Scaffidi et al, 1998). 

Signal Receptor Transducer Effector Response, upstream downstream... 

Odorants are thought to bind to integral membrane receptors on the cilia of the olfactory sensory neurons. The receptors are thought to he specific different olfactory neuron types recognize different odorants that share certain characteristics (Buck, 1993). The odorant receptors transduce signals via interactions with G-proteins (so-called because guanosine trisphosphate is involved in their activation). These G-protein-coupled exhibit seven hydrophobic domains (Fig. 5.6). Variation in the amino acid sequence of the transmembrane domain may account for specificity and selectivity of odor reception. 

A. Some cell-surface receptors transduce their signals by means of a kinase cascade initiated by their protein tyrosine kinase activity (Figure l4-4). 

Cell surface receptors receive the signal (e.g. a chemical messenger) at the outside of the cell, become activated and initiate a signaling chain in the interior of the cell. In such signaling pathways the membrane bound receptor transduces the signal at the cell membrane so that it is not necessary for the signal to actually enter the cell. 

It has been specifically focused on responses to chronic hypoxia that involve adenosine-induced changes in the transcription regulator HIF-1 expression. In particular, it has been investigated the correlation between adenosine receptor stimulation and/or blockade and HIF-la expression modulation in hypoxia. It has been demonstrated that adenosine is able to increase HIF-la protein expression in response to hypoxia in a dose- and time-dependent manner in human melanoma, glioblastoma and tumor colon cells (Merighi et al. 2005,2006,2007). These results indicate that the cell surface A3 adenosine receptor transduces extracellular hypoxic signals into the cell interior. 

C-Jun-N-terminal kinases The JNK/Stress-activated protein kinases (SAPKs) do not respond well to mitogens but are strongly activated by agents that induce cellular stress. These kinases phosphorylate C-Jun transcription factor. The sequence of the tripeptide motif for JNK is Thr-Pro-Tyr. The activators of cytokine and tyrosine kinase receptors transduce signal to the upstream MAPKKKs. These... 

When natural or synthetic DNA molecules interact with electrode surfaces adsorption occurs. The knowledge about the adsorption of nucleic acids onto the electrode surface leads to the development of DNA-modified electrodes, also called electrochemical DNA biosensors [3-6,19-24], An electrochemical DNA biosensor is an integrated receptor-transducer device that uses DNA as the biomolecular recognition element to measure specific binding processes with DNA, using electrochemical transduction. 

In any case, such direct binding measures of the dopamine receptor in the AP provides new dimensions in the understanding of the functional role of dopamine in the gland. The detailed examination of the dynamics of the dopamine receptor in the AP offers the simplest model of studying postsynaptic dopamine receptors in isolation and will further our understanding of dopamine receptor-transduced signals in the brain. 

GABA glycine receptors transducing components (for inhibitory synapses)... 

First, mention can be made of cases in which the measured effect instead of being proportional to the activated receptors, follows a more general function E = T (v). This model is called receptor-transducer and was introduced by Black and Leff [409]. The function T is called a transducer function and its most common form is yet again the Emax function, which when replaced in (10.5) results in an Emax model but with different shape parameters called an operational model [441]. 

Kihara T, Shimohama S, Akaike A (1999) Effects of nicotinic receptor agonists on beta-amyloid beta-sheet formation. Jpn J Pharmacol 79 393-396 Kihara T, Shimohama S, Sawada H, Honda K, Nakamizo T, Shibasaki H, Kume T, Akaike A (2001) alpha 7 nicotinic receptor transduces signals to phosphatidylinositol 3-kinase to block A beta-amyloid-induced neurotoxicity. J Biol Chem 276 13541-13546 Kihara T, Shimohama S, Urushitani M, Sawada H, Kimura J, Kume T, Maeda T, Akaike A (1998) Stimulation of alpha4beta2 nicotinic acetylcholine receptors inhibits beta-amyloid toxicity. Brain Res 792 331-334... 

Yamashita, T, Higuchi, H, Tohyama, M, The p75 receptor transduces the signal from myehn-associated glycoprotein to Rho, J. Cell. Biol, 157, 565-570, 2002. 

Biosensors can be defined as an integrated receptor-transducer device that is capable of providing selective quantitative or semi-quantitative analytical information using a biological recognition element. A biosensor converts a biological event into a detectable... 

The CBi cannabinoid receptor is the major mediator of the psychoactive effects of cannabis and its derivatives. In addition, this G protein-coupled receptor transduces many of the effects of the endogenous cannabinoids. Understanding the distribution of CBi receptors has proved helpful to both predict and understand the effects of cannabinoids. For example, the high CBi receptor levels found in cortex, basal ganglia, and cerebellum coincide with the prominent effects cannabinoids have on functions subserved by these brain regions. By comparison, the low levels present in the medullary nuclei responsible for regulating respiration are consistent with the modest effects cannabinoids have on respiratory drive. Furthermore, the strong presynaptic localization of the receptor found in ultra-structural studies underscores its major role as a modulator of neurotransmitter release. 

Opiates Regulates chemokine receptor-transduced signal Reduces chemokine-induced migration in vitro... 

---