Lennart A. Ransnäs's research while affiliated with University of Gothenburg and other places

... It was shown that peptides, derivatives of C-terminal sites of the Gα s , very different in length disturb by the competitive mechanism the functional interaction of receptors and G s proteins and change the affinity of receptors for hormones [66,77,[143][144][145][146][147][148][149][150][151]. The expression of 83-mer polypeptide derived from C-terminal region of the Gα s induces the inhibition of β 2 -AR-and D 1A -DR-mediated cAMP production in HEK293 cells [146]. ...

... Several independent investigators reported translocation of G protein a subunits from plasma membranes to the cytosol as a direct consequence of stimulation by various agonists (Takahashi et al. 1992;Yajima et al. 1993;Svoboda and Milligan 1994). Such behavior has been shown for a subunits of different G proteins, but G s a appears to be one of the most prominent and controversial in this respect (Ransnas and Insel 1988;Milligan and Unson 1989;Ransnas et al. 1989Ransnas et al. , 1991Ransnas et al. , 1992Negishi et al. 1992;Iiri et al. 1996;Yajima et al. 1998;Huang et al. 1999;Witte et al. 1999). Interestingly, soluble forms of some G proteins have also been detected under resting (i.e. ...

... GST-Ric-8 proteins are mostly cytosolic, whereas functional endogenously expressed G proteins are viewed to reside predominantly on the plasma membrane with only a small subfraction present in the cytosol. Studies have shown that a population of some G proteins becomes released from the plasma membrane into a soluble fraction upon GPCR agonist treatment (42)(43)(44)(45). Perhaps a function of Ric-8 is to bind the G␣ released into the cytosol and recycle it back to the plasma membrane. ...

... 15 Although PEG mediated precipitation is a simple method, it is also incompatible with PCR. 16,17 Recently, an alternative approach has been studied using a bead-mediated capture method. ...

... Recently identified STb variant H12N was reported to bind the same receptor [57]. Once bound, STb is internalized [58], followed by a dose-dependent influx of extracellular Ca 2+ through the activation of pertussis toxin-sensitive GTP-binding regulatory protein and receptor-operated Ca 2+ channel [59,60]. Intracellular increase in Ca 2+ levels in response to STb leads to binding of Ca 2+ to its receptor calmodulin, which results in the formation of Ca 2+ -calmodulin complex that promotes activation of calmodulin-dependent protein kinase II (CAMKII) [61]. ...

... One possible underlying mechanism for EA pretreatment to produce cardiac protection and an antiarrhythmic effect may be to influence the activity of the sympathetic nervous system so as to protect the cardiac β-ARs from sympathetic overstimulation during subsequent ischemia and reperfusion. Sympathetic activity [2, 15], catecholamines [2], and β 1 -AR [16, 17] are shown to be associated with both myocardial injury of ischemia and reperfusion. The ischemic injury of myocardium was due, at least partially, to the overexcitation of the sympathetic nervous system [1] and hyperactivity of cardiac β-ARs [18]. ...

... It was initially characterized as a good inducer of mast cell degranulation [80], and later was found to increase cytosolic calcium concentration and to stimulate IP3 production in human neutrophils [83]. These latter effects could be explained by the direct interaction of mastoparan with Gi proteins and stimulation of the GTPase activity, resulting in PLC activation, IP3 release and cytosolic calcium elevation [84,85]. Mastoporan induces neutrophil chemotaxis, degranulation, CR3 expression and superoxide production [85,86]. ...

... Detection of low concentrations of biomolecules, such as hormones, proteins, nucleic acids and low molecular weight metabolites, is crucial in many clinical and research applications [1][2][3]. One of the most effective detection methods is affinity binding to a suitable receptor or ligand. ...

... Because PKA targets include Ser 16 -PLB, which increases the calcium uptake to SR and contributes to positive inotropic and lusitropic effects [4], it is suggested that a reduced β-AR-mediated PKA activation could explain not only contractile and relaxing dysfunctions in steady state (reduced +dF/dt max and −dF/dt max , respectively), but also the depressed inotropic response to isoproterenol in the PWM group. Interestingly, Ransnäs et al. [33] reported that β-AR content is not changed in rats submitted to protein-calorie deprivation for two weeks, associated with an increased affinity of the β-AR to isoproterenol. About this, we believe the inconsistency between these results may be due to differences in duration of malnutrition and the diets used to induce malnutrition. ...

... It is not known how efficiently heterotrimers are loaded onto endocytic vesicles at the plasma membrane, how receptor activation might change this process, or what the fate of G proteins might be after endocytosis. Activation at the plasma membrane promotes heterotrimer dissociation, and the resulting loss of membrane avidity allows Gbg dimers and some Ga subunits to translocate through the cytosol to sample intracellular membranes (Akgoz, Kalyanaraman, & Gautam, 2004;Hynes et al., 2004;Ransnäs et al., 1989;Slepak & Hurley, 2008;Wedegaertner, Bourne, & von Zastrow, 1996). However, these processes reverse quickly when activation ceases (Akgoz, Kalyanaraman, & Gautam, 2004), meaning that activation-dependent translocation of free Ga subunits and Gbg dimers would be an inefficient mechanism to deliver inactive heterotrimers to intracellular membranes. ...