Basal Activity

Basal activity is the enzymatic or other activity of a protein normally governed by interaction with a ligand or other activator molecule in the absence of that activator. 

Large granular lymphocytes, not belonging to either the T- or B-cell lineage. Natural killer (NK) cells are considered part of the innate defense system since, in contrast to cytotoxic T-cells, they are able to kill certain tumor cells in vitro without prior sensitization. The basal activity of NIC cells increases dramatically following stimulation with type I IFNs. In addition, NK cells display Fc-receptors for IgG and are important mediators of Antibody-Dependent-Cell-mediated-Cytotoxicity (ADCC). 

Bartter s Syndrome Basal Activity Basal Ganglia Basement Membrane Basophils Bax... 

Additionnally, we show that the PG activity of the SCPP strain is regulated. It is stimulated by polyglacturonic acid concentrations similar to the ones seen in various fruit juices. On an industrial point of view, this induction would be diminished by the elevated glucose concentrations found in these fruit juices when compared to the pectin concentrations. Basal activities would be sufficient to eliminate all pectins and obtain juice stabilization. It would also have been interesting to study the effect of glucose concentrations of 15% and 20% (concentrations found in fruit juices, beers and ciders) on the PG activity of the SCPP strain. 

The possibility that the depression in basal activity may have some other explanation (e.g., an inhibitory action on one or more of the events that follow receptor activation) should not be overlooked. 

Scheper, G. C., Morrice, N. A., Kleijn, M., and Proud, C. G. (2001). The MAP kinase signal-integrating kinase Mnk2 is an eIF4E kinase with high basal activity in mammalian cells. Mol. Cell. Biol. 21, 743-754. 

The involvement of the carboxy terminal in the G protein coupling of the mGluR is perhaps best illustrated by the significant differences in agonist potencies, signaling kinetics, and basal activities between the long-tailed and short-tailed Group I... 

Basal enzyme levels for control fish in the Venezuelan crude experiment (Table V) were higher than the control values for experiments with pure hydrocarbons (Table IV). Increase in basal activity was correlated with an increase in water temperature and the initiation of feeding. Enzyme activity was consistently low in cunners during the winter, and appears to rise in late spring to a summer peak (24). 

Fig. 12.4 Functional coupling of the Gly389 and Arg389 receptors to adenylyl cyclase. (Reproduced from ref. 26 with permission of the American Society for Biochemistry and Molecular Biology.) Shown are the results from studies with clonal lines expressing each receptor at matched levels and the data presented as absolute activities (A) and normaUzed to the stimulation by forskolin (B). The results of similar studies with two other clonal lines are shown in C and D. The Arg389 demonstrated small increases in basal activities and marked increases in agonist-stimulated activities compared with the Gly389 receptor. Shown are the mean results from four independent experiments carried out with each line. Absent error bars denote that standard errors were smaller than the plotting symbol...

A true antagonist lacking intrinsic activity ( neutral antagonist ) displays equal affinity for both the active and inactive states of the receptor and does not alter basal activity of the cell. According to this model, a partial agonist shows lower selectivity for the active state and, to some extent, also binds to the receptor in its inactive state. 

CaM, their eflfect on the activity of two CaM-dependent en2ymes, namely PDEl and NADK, was investigated. All the tested compounds except citrinin (53) showed significant inhibitory effect on PDE activity in a concentration-dependent manner [IC50 values for compounds 44—52 were 8.1 xM, 7.2 xM, 6.1 xM, 5 8 xM, 7.6 xM, 6.6 xM, 4.8 xM, 4.7 xM and 5.2 xM, respectively]. The inhibitory activity was higher or comparable to that of chlorpromazine (IC50 = 10.6 xM). It is important to point out that none of the tested compounds affected the basal activity of PDE at the concentrations tested. 

There is recent evidence that a third form of interaction is possible. If a receptor system has a basal activity without a receptor-agonist interaction then there exist the possibility of an so-called inverse ag-onism, that is a drug that actually inhibits the basal activity as a result of its binding to the receptor. This phenomenon has been shown for various sympatholytic drugs. 

GC, in turn, exert a very sensitive negative feedback on the HPA system at the level of the paraventricular nucleus of the hypothalamus (PVN) and the anterior pituitary, and also at the level of the hippocampus, which projects to the bed nucleus of the stria terminalis, the latter which sends off projections to the PVN. In concert with other components of the stress hormone system, the action of corticosterone displays two modes of operation (for review see De Kloet et al. 1998). In the first proactive mode, GC maintain basal activity of the HPA system and control the sensitivity or threshold of the system s response to stress. GC promote coordination of circadian events, such as the... 

The lipidosterolic extract, in Chinese hamster ovary cells, reduced the basal activity of a K channel and of protein kinase (PK) C. Pretreatment of the cells with the extract for 6-36 hours abolished the effects of prolactin on Ca 3 K conductance and PKC. The results indicated that the extract can block prolactin-induced prostate growth by inhibiting several steps of prolactin receptor signal transduction . 

There are two main hypotheses about the involvement of endogenous opioid systems in the maintenance of self-injurious behaviors (Sandman, 1988 Buitelaar, 1993). The pain hypothesis suggests that in some subjects self-injury does not induce pain because excessive basal activity of opioid systems in the CNS has led to an opioid analgesic state. The addiction hypothesis posits that particularly repetitive and stereotyped forms of self-injury stimulate the production and release of en-dogeneous opioids. Therefore, chronic maintenance of self-injury may be due to addiction to endogenous opioids or to positive reinforcement by a central release of opioids triggered by the self-injurious behavior. Irrespective of which hypothesis one favors, treatment with opiate antagonists seems to be a rational approach. 

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