scholarly journals Divalent cations increase the binding capacity of the (3H)mepyramine binding site, a possible histamine H1 receptor, in rat liver membranes.

1989 ◽  
Vol 49 (3) ◽  
pp. 351-355
Author(s):  
Hiroyuki FUKUI ◽  
Nai Ping WANG ◽  
Sadako SAWAI ◽  
Fumi TANAKA ◽  
Hiroshi WADA
Keyword(s):  
Binding Site ◽  
Rat Liver ◽  
Binding Capacity ◽  
Divalent Cations ◽  
H1 Receptor ◽  
Histamine H1 Receptor ◽  
Liver Membranes

scholarly journals The role of Asp-107, the putative binding site of histamine, in histamine H1 receptor functions.

1994 ◽  
Vol 64 ◽  
pp. 168
Author(s):  
Kazumi Ota ◽  
Katsumi Fujimoto ◽  
Ikuo Imamura ◽  
Hideyuki Hayashi ◽  
Hiroyuki Kagamiyama ◽  
...  
Keyword(s):  
Binding Site ◽  
H1 Receptor ◽  
Histamine H1 Receptor ◽  
Putative Binding Site

Binding of [14,15-3H]14,15-dihydroforskolin to rat liver membranes: comparison with the stimulatory effect of forskolin on adenylate cyclase

1987 ◽  
Vol 65 (5) ◽  
pp. 803-809 ◽  
Author(s):  
Kurt Schmidt ◽  
Hans P. Baer ◽  
Azim Shariff ◽  
William A. Ayer ◽  
Lois Browne
Keyword(s):  
Adenylate Cyclase ◽  
Rat Liver ◽  
Binding Sites ◽  
Binding Capacity ◽  
Protein A ◽  
High Specificity ◽  
Binding Studies ◽  
Liver Membranes ◽  
High Concentrations ◽  
Equilibrium Dissociation

The binding of [14,15-3H]14,15-dihydroforskolin ([3H]DHF) to rat liver membranes has been further characterized and was compared with the stimulatory effect of forskolin on adenylate cyclase. The binding equilibrium dissociation constant (KD) for 14,15-dihydroforskolin obtained in inhibition experiments was 0.6 μM, with a maximal binding capacity (Bmax) of 114 pmol/mg protein. A similar KD value (0.5 μM) was derived from kinetics studies that revealed very rapid association and dissociation reactions. For structure–activity relationship studies several forskolin derivatives were synthesized and tested for their ability to inhibit [3H]DHF binding and increase adenylate cyclase activity. Among the tested compounds, forskolin itself was the most potent agonist (KI = 0.2 μM). Further modification of the molecule in position 7 and (or) 1 decreased or abolished its agonist properties in both adenylate cyclase and binding studies. [3H]DHF binding was not affected by several nucleotides, carbohydrates, lectins, and hormone receptor agonists including isoproterenol, glucagon, and adenosine, but the steroids 17-β-estradiol, progesterone, and testosterone showed slight inhibitory effects at unphysiologically high concentrations, [3H]DHF binding and forskolin-stimulated adenylate cyclase were sensitive to heat and N-ethylmaleimide treatment. Forskolin protected adenylate cyclase against inactivation by heat but not by N-ethylmaleimide. Preincubation of the membrane with trypsin decreased [3H]DHF binding. The results presented in this study demonstrate that the binding sites identified with [3H]DHF have a high specificity for forskolin and provide evidence that these binding sites are involved in the stimulation of adenylate cyclase by forskolin.

Analysis of the lipoprotein binding site of rat liver membranes

1994 ◽  
Vol 72 (3-4) ◽  
pp. 132-142 ◽  
Author(s):  
Lynda Adam ◽  
Louise Brissette
Keyword(s):  
Membrane Proteins ◽  
Rat Liver ◽  
Binding Sites ◽  
Plasma Membranes ◽  
Binding Capacity ◽  
New Information ◽  
Liver Membrane ◽  
Liver Membranes ◽  
Bona Fide ◽  
Lipoprotein Binding

Intermediate density lipoproteins (IDL) were shown to bind to high- and low-affinity binding sites on rat liver membranes. The low-affinity sites were named lipoprotein binding sites (LBS), since they bind all classes of lipoproteins. This study was undertaken to further characterize the interaction of 125I-labelled IDL with the LBS of rat liver membranes to determine the chemical nature of the LBS. We found that the binding of IDL to the LBS is insensitive to EDTA and sensitive to heparin and that it is present on plasma membranes. Also, membranes were pretreated with various enzymes that have an effect on the membrane constituents, and the activity of the LBS on these treated membranes was determined. Our results reveal that the LBS of rat liver membranes is insensitive to heparinase I, chondroitinase ABC, and phospholipase C, while it is partially sensitive to phospholipase A2 and sensitive to proteases and heat. Rat liver membrane proteins were solubilized with Triton X-100, reconstituted in liposomes, and analyzed for their ability to bind lipoproteins. 125I-labelled IDL were shown to bind to high- and low-affinity sites that are similar, in affinity and specificity, to the ones observed with intact rat liver membranes, indicating that a LBS activity is detectable on these liposomes. We found that the binding capacity of low-affinity sites in liposomes containing either no protein or containing proteins solubilized from Escherichia coli membranes is five times weaker than low-affinity sites in liposomes containing liver membrane proteins. Thus, a protein solubilized from rat liver membranes has LBS activity when reconstituted in liposomes. Taken altogether our results provide new information on the binding of IDL to the LBS and indicate that the LBS activity is in part mediated by a protein. Thus, the LBS appears to be a bona fide receptor.Key words: lipoprotein, receptor, binding, metabolism.

scholarly journals Is the mepyramine binding site only histamine H1-receptor ?

1992 ◽  
Vol 58 ◽  
pp. 156
Author(s):  
Yeqi Liu ◽  
Hiroyuki Fukui ◽  
Yoshiyuki Horio ◽  
Hiroyuki Mizuguchi ◽  
Ikuo Imamura ◽  
...  
Keyword(s):  
Binding Site ◽  
H1 Receptor ◽  
Histamine H1 Receptor
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