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181.
Association of spectrin with desmin intermediate filaments 总被引:5,自引:0,他引:5
The association of erythrocyte spectrin with desmin filaments was investigated using two in vitro assays. The ability of spectrin to promote the interaction of desmin filaments with membranes was investigated by electron microscopy of desmin filament-erythrocyte inside-out vesicle preparations. Desmin filaments bound to erythrocyte inside-out vesicles in a spectrin-dependent manner, demonstrating that spectrin is capable of mediating the association of desmin filaments with plasma membranes. A quantitative sedimentation assay was used to demonstrate the direct association of spectrin with desmin filaments in vitro. When increasing concentrations of spectrin were incubated with desmin filaments, spectrin cosedimented with desmin filaments in a concentration-dependent manner. At near saturation the spectrin:desmin molar ratio in the sedimented complex was 1:230. Our results suggest that, in addition to its well characterized associations with actin, spectrin functions to mediate the association of intermediate filaments with plasma membranes. It might be that nonerythrocyte spectrins share erythrocyte spectrin's ability to bind to intermediate filaments and function in nonerythroid cells to promote the interaction of intermediate filaments with actin filaments and/or the plasma membrane. 相似文献
182.
183.
N A Sharif N S Pilotte D R Burt 《Biochemical and biophysical research communications》1983,116(2):669-674
Receptors for thyrotropin-releasing hormone (pGlu-His-Pro-NH2, TRH) on thaw-mounted sections of rabbit spinal cord have been identified biochemically and visualized by light microscopic autoradiography. Binding of [3H] [3-Me-His2]TRH to 20 microns sections exhibited high apparent affinity and a pharmacological specificity almost identical to that previously demonstrated for spinal TRH receptors in membranes. In autoradiograms, the highest density of TRH receptors appeared in the substantia gelatinosa of the dorsal gray and around the central canal, with intermediate levels in the ventral gray. 相似文献
184.
Epinephrine-promoted release of [3H]guanylylimidodiphosphate ([3H]Gpp(NH)p) from human platelet membranes has been used to probe the interactions between alpha2-adrenergic recpetors and Ni, the guanine nucleotide binding protein that couples those receptors to an inhibition of adenylate cyclase activity. We show here that ADP, which also acts through specific platelet receptors to inhibit adenylate cyclase activity, also promotes the release of [3H]Gpp(NH). The amount of [3H]Gpp(NH)-release elicited by epinephrine and by ADP together is equal to the sum of the amounts released by the two agents acting individually. Furthermore the maximal amounts of [3H]Gpp(NH)-release elicited by each of the two agents approximates the numbers of receptors for ADP and epinephrine present in the platelet membranes. These results suggest that the two receptor types interact with distinct portions of the pool of Ni molecules and that each receptor initiates guanine-nucleotide exchange on a single molecule of Ni. 相似文献
185.
The binding parameters of the oligomycin-sensitivity conferring protein (OSCP) in inside-out particles from beef heart mitochondria have been tested by means of two assays, the oligomycin-sensitive ATP-Pi exchange, and the oligomycin-sensitive ATP hydrolysis. The total number of OSCP binding sites in A particles was equal to 220 pmol/mg particle protein. Each mole of ATPase active site was able to bind 1.1 +/- 0.5 mol OSCP with Kd 1.7 nM. 相似文献
186.
Marion T. Hierowski 《FEBS letters》1983,154(1):92-96
Quantitative analyses of LH-RH-like membrane receptors were performed in five tumors from the transplantable Dunning R3372H rat prostatic adenocarcinoma. The binding of D-Trp6-LH-RH, an agonist of LH-RH, was observed in all 5 tumors. The antagonist [Ac-Dp-Cl-Phe1,2,D-Trp3,D-Lys6,D-Ala10]-LH-RH was bound to 4 tumors. The apparent equilibrium dissociation constant (Kd) for D-Trp6-LH-RH receptor was from 2.6–3.9 × 10?10 M. The apparent equilibrium Bmax values (maximum number of binding sites) were from 17.2–86.0 fmol/mg membrane protein for D-Trp6-LH-RH receptor. The Kd for the antagonist was from 2.4–2.7 × 10?10 M and the Bmax values were from 35.5–66.0 fmol/mg membrane protein. Similar binding studies performed in 6 normal rat prostates showed no binding capacities. 相似文献
187.
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189.
The temperature dependence of the kinetics of the binding of ATP to myosin subfragment-1 was studied by an ATP chase technique in a rapid-flow-quench apparatus: (formula; see text) A temperature range of 30 degrees C to -15 degrees C was obtained with ethylene glycol as antifreeze. The Arrhenius plot of k2 is discontinuous with a jump at 12 degrees C. Above the jump delta H+ = 9.5 kcal/mol, below delta H+ = 28.5 kcal/mol. Few such Arrhenius plots are recorded in the literature but they are predicted from theory. Thus, we explain our results as a phase change of the subfragment 1-ATP system at 12 degrees C. This is in agreement with certain structural studies. 相似文献
190.
E.K. Rooney J.M. East O.T. Jones J. McWhirter A.C. Simmonds A.G. Lee 《生物化学与生物物理学报:生物膜》1983,728(2):159-170
We present a method by which it is possible to describe the binding of fatty acids to phospholipid bilayers. Binding constants for oleic acid and a number of fatty acids used as spectroscopic probes are deduced from electrophoresis measurements. There is a large shift in value for the fatty acids on binding to the phospholipid bilayers, consistent with stronger binding of the uncharged form of the fatty acid. For dansylundecanoic acid, fluorescence titrations are consistent with the binding constants derived from the electrophoresis experiments. For 12-(9-anthroyloxy)stearic acid, fluorescence and electrophoresis data are inconsistent, and we attribute this to quenching of fluorescence at high molar ratios of 12-anthroylstearic acid to phospholipid in the bilayer. 相似文献