Phosphatidyl inositol turnover

In the human gastric tumoral cell line HGT1, (R)a-methylhistamine has shown to inhibit in a nanomolar range basal and carbachol-stimulated inositol phosphate formation (Cherifi et al., 1992) This suggests the presence of H3 receptors on ECL and/or on parietal cells, that are coupled with phosphatidyl inositol turnover. 

This tricyclic analog (84) lacked serotoninlike affinity for 5-HT, receptors, but it demonstrated high and selective affinity for 5-HT, receptors. Like serotonin, it stimulated phosphatidyl inositol turnover in rat brain slices. The low affinity for 5-HT, receptors was rationalized, in part, on the basis of steric interference between the dihydropyran ring and the aminoethyl side chain, which inhibits the tiyptamine system from assuming the folded ergotlike conformation, as illustrated in (85), which probably approximates the conformation of serotonin at 5-HT, receptors. The methyl ether of serotonin exhibits approximately the same affinity for 5-HT sites as does serotonin (51). The methyl ether also has marked affinity for 5-HT and 5-HT receptors, but it has diminished affinity (compared with serotonin) at 5-HT receptors. It was... 

Glutamate or a structurally-similar chemical is an excitatory neurotransmitter in many areas of the brain. EAA receptors are generally divided into N-methyl-D-aspartate, quisqualate and kainate receptors, named for agonists that bind to each type of receptor. Further subdivision of classes is currently underway. Stimulation of EAA receptors increases cation conductance, leading to depolarization, or stimulates phosphatidyl inositol turnover. 

Piericidins are insecticidal compounds isolated from mycelia of Streptomyces mobaraensis and Streptomyces pactum. They are toxic to several species of insects, aphids, and mites. Piericidin A is known to block electron transport between NADH dehydrogenase and coenzyme Q. In the course of our screening for phosphatidyl-inositol turnover inhibitors, we isolated the novel antibiotics piericidin W-oxide (29), as well as B5 and B5 N-oxide (30), from Streptomyces (Fig. 17). 

The 5-HT2 receptor "family and the stimulation of phosphatidyl inositol turnover. 

MUSCARINIC CHOLINERGIC STIMULATION OF PHOSPHATIDYL INOSITOL TURNOVER IN THE CNS... 

Dawson and Irvine (1978) noted that in many of those tissues in which physiological stimuli caused activation of phosphatidyl-inositol turnover, the same stimuli caused an increase in prostaglandin release. Such activation of phosphatidyl-inositol turnover and augmented production of... 

A patient with manic depressive disorder is treated with litfaium, which slows the turnover of inositol oqihates and the phosphatidyl inositol derivatives in cells. Which of the following protein kinases is most directly affected by this drug ... 

Recently, it was shown that inositol trisphosphate could induce calcium release and vasoconstriction in permeabilized rabbit pulmonary artery. Perhaps, as in the platelet, the TXA2/PGH2 receptor is coupled to phosphatidyl-inositol polyphosphate turnover. 

Our results show that the components of the phosphatidyl inositol cycle are present in suspension cultured tobacco cells, which is in agreement with previous report (5). The incorporation of [ P] into phosphoinositides was rather fast, preferentially into PIP which peaked at 5 min (70% of tot. inc.) and then levell (fig lb). The fast incorporation of [ P] into PIP, PIP2 and PA is considered as a the result of rapid phosphoinositide turnover (3). Moreover, changes in the [ P] PA to PI ratio are good indicators of the rapid biosynthesis of the major membrane phospholipids. In tobacco cells we noted a lack of response of PIP2 to cold stress or to added substances as choline chloride or ABA to the culture medium. Cold temperature resulted in an enhanced level of PA and PIP suggesting that Pl-kinase and the enzymes involved in PA formation (e.g. DAG-kinase and phospholipases C and D) remained active in cold. 

Many oncogenes such as ras, src, sis, fms, and fes enhance cellular PI turnover. Phosphatidyl breakdown by phospholipase C generates two second messengers, diacyIglycerol and inositol trisphosphate. The formed directly activates protein kinase C, and the latter binds to the receptor on endoplasmic reticulum to mobilize calcium ions. Therefore, we screened culture filtrates of microorganisms for inhibitors of PI turnover and thus isolated psi-tectorigenin (Fig. 11, ref. 23). ... 

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