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1.
Solubilized Ca2+, Mg2+-ATPase of sarcoplasmic reticulum was phosphorylated with ATP without added MgCl2. The phosphoenzyme formed was ADP-sensitive. Ca2+ in the medium was chelated after phosphorylation. This induced a slow transition of the phosphoenzyme from ADP-sensitive to ADP-insensitive forms. The ADP-sensitivity was restored by subsequent addition of CaCl2. These results showed that the transition was caused by dissociation of Ca2+ bound to the phosphoenzyme. Further observations indicated that, when Ca2+ in the medium was chelated, Ca2+ bound to the phosphoenzyme was dissociated much more slowly than Ca2+ bound to the dephosphoenzyme. This suggests a possible formation of the occluded form of the Ca2+-binding site in the phosphoenzyme. 相似文献
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3.
Highly purified Na+, K+-ATPase of the dog kidney was reacted with Mg2++32Pi or Mg2++32Pi + ouabain. 32P-phosphorylation was terminated by the addition of EDTA, and the effects of various ligands on dephosphoration rate were studied. ATP reduced the dephosphorylation rates of both the native and the ouabain-complexed enzymes. K0.5 for this effect of ATP was about 0.2 mM. ADP also slowed dephosphorylation, but less effectively than ATP. The ATP effect on the native enzyme, but not that on the ouabain-complexed enzyme, was antagonized by Na+. The data establish the binding of ATP to the phosphoenzyme. Since the site that is phosphorylated by Pi is the same that is phosphorylated by ATP, coexistence of two ATP sites on the functional unit of the enzyme is suggested. 相似文献
4.
Vitamin A acid-induced activation of Ca2+-activated, phospholipid-dependent protein kinase from rabbit retina 总被引:2,自引:0,他引:2
S Ohkubo E Yamada T Endo H Itoh H Hidaka 《Biochemical and biophysical research communications》1984,118(2):460-466
Ca2+-activated, phospholipid-dependent protein kinase from rabbit retina was partially purified. Vitamin A acid (retinoic acid) stimulated this protein kinase in the presence of Ca2+, while other metabolites of vitamin A such as retinol or retinal were less effective. The order of the extent of phosphorylation of the various substrate proteins by this protein kinase was identical in the presence of vitamin A acid or phosphatidylserine. The major spots of the 32P labeled peptide from histone H1 phosphorylated in the presence of vitamin A acid by this protein kinase did not differ from those obtained from histone H1 phosphorylated in the presence of phosphatidylserine. Retinol caused a further enhancement of the enzymatic activity, whereas the addition of retinal inhibited the activation by vitamin A acid. Thus, vitamin A and its metabolites may play an important role in the regulation of Ca2+-activated, phospholipid-dependent protein kinase activity in the retina. 相似文献
5.
T.W. Barrett 《Biochimica et Biophysica Acta (BBA)/General Subjects》1975,385(1):157-161
Hyaluronic acid transduces a very gentle pressure into an electrical potential. Such pressure, depending on its direction, changes the optical rotary dispersion properties of the salt, either increasing the rotation in the direction already shown by the unpressured salt or changing and increasing the rotation in the opposite direction. These findings have implications for understanding the funtion of the cochlear and vestibular fluids, renal function, and the approximation to frictionless motion of normal joints. 相似文献
6.
Molecular diversity of calpastatin in mammalian organs 总被引:1,自引:0,他引:1
E Takano N Yumoto R Kannagi T Murachi 《Biochemical and biophysical research communications》1984,122(3):912-917
The crude homogenates of various human and porcine organs were subjected to immunoelectrophoretic blot analysis using affinity-purified anti-calpastatin antibody which specifically reacts with human erythrocyte 70 kDa calpastatin. Multiple immuno-reactive bands were revealed which ranged from 100 to 50 kDa. The results indicated the diversity of monomeric calpastatin molecules. The band patterns were different from one organ to the other. Among them, lung, heart and skeletal muscle were characterized by the predominance of 90-100 kDa calpastatin, having a common antigenicity to erythrocyte 70 kDa calpastatin. Such molecular diversity of calpastatins was also substantiated by enzymatic and chromatographic analyses. 相似文献
7.
In the rat both hypothyroidism and diabetes decrease heparin-releasable liver lipase activity. This defect may be reversed by feeding a diet rich in polyunsaturated fatty acids. It is suggested that a diet-induced increase of membrane fluidity restores liver lipase activity, which contributes to the hypolipidemic effect of polyunsaturated fatty acids. 相似文献
8.
Calcium-dependent regulator, a calcium-binding protein isolated from brain and adrenal medulla, has been shown to activate a brain calcium-sensitive cyclic nucleotide phosphodiesterase. To determine if this protein has the same role in the adrenal medulla, the cyclic nucleotide phosphodiesterase of adrenal medulla was characterized. Neither crude nor partially purified adrenal medullary phosphodiesterase was inhibited by EGTA or stimulated by calcium and the calcium-dependent regulator, whereas similar brain preparations displayed sensitivity to these agents. As the calcium-dependent regulator does not appear to stimulate adrenal medullary cyclic nucleotide phosphodiesterase activity, alternate roles of this protein in adrenal medulla are suggested. 相似文献
9.
Synthetic substance P stimulated adenylate cyclase activity in particulate preparations from rat and human brain.The concentration of substance P for half maximal stimulation in rat brain was 1.8 · 10−7 M.The stimulatory effect of substance P on the rat brain adenylate cyclase activity was 88% compared with 48% by noradrenalin, 163% by prostaglandin E1 and 184% by prostaglandin E2.Both the basal and substance P-stimulated adenylate cyclase activity in rat brain were inhibited by concentration of Ca2+ above 10−6 M.The chelating agent ethyleneglycol-bis-(β-aminoethylether)-N,N′-tetraacetic acid at a concentration of 0.1 mM reduced the basal adenylate cyclase activity by 64% and eliminated the substance P-stimulated activity.The inhibition by ethyleneglycol-bis-(β-aminoethylether)-N,N′-tetraacetic acid was completely reversed by increasing concentrations of Ca2+. 相似文献
10.
M Solti P Dévay I Kiss J Londesborough P Friedrich 《Biochemical and biophysical research communications》1983,111(2):652-658
Like adult heads and whole flies, larval brains of wild type Drosophila melanogaster contain two major soluble cyclic nucleotide phosphodiesterases, forms I and II. Larval brains of the learning-defective mutant strain, dunceM11, contain only the form I enzyme. In both wild type and dunce strains the form I enzyme is activated by Ca2+/calmodulin. A time-dependent loss of this Ca2+ activation was observed. 相似文献
11.
N Narayanan P Lee M Newland R L Khandelwal 《Biochemical and biophysical research communications》1982,108(3):1158-1164
A cytosolic protein fraction, termed CPF-I, derived by (NH4)2 SO4 fractionation of rabbit heart cytosol caused marked inhibition (up to 95%) of ATP-dependent Ca2+ uptake by cardiac sarcoplasmic reticulum. The inhibitory effect of CPF-I was concentration-dependent (50% inhibition with ~ 80–100 μg CPF-I) and heat labile. The inhibitor reduced the velocity of Ca2+ uptake without altering the apparent affinity of the transport system for Ca2+. Concomitant with the inhibition of Ca2+ uptake, Ca2+-sensitive ATP hydrolysis was also inhibited by CPF-I. The inhibitor did not cause release of Ca2+ from Ca2+-preloaded membrane vesicles. The inhibitor activity of CPF-I could be adsorbed to a DEAE cellulose column and could be eluted with a linear gradient of KCl. These results demonstrate the presence of a soluble protein inhibitor of sarcoplasmic reticulum calcium pump in cardiac muscle and raises the intriguing possibility of its participation in the regulation of calcium pump . 相似文献
12.
The chelating agents, ethylene glycol bis-(β-aminoethyl ether)-N,N′-tetraacetic acid (EGTA) and EDTA, had no effect on the initial interaction of phytohemagglutinin with lymphocytes at concentrations which have been shown previously to inhibit the development of the phytohemagglutinin response completely. However, they had a marked inhibitory effect on uptake of the amino acid analog, α-aminoisobutyric acid in both unstimulated and phytohemagglutinin-stimulated cells. The inhibition of amino acid uptake by EGTA could be reversed by adding Ca2+ but not Mg2+. These results demonstrated that Ca2+ is not essential to the initial interaction of phytohemagglutinin with the cell, but does influence amino acid transport which may be a critical preparatory event for later increased protein synthesis. 相似文献
13.
Release and activation of phosphorylase phosphatase upon rupture of organelles from rat liver 总被引:6,自引:0,他引:6
Liver extracts (8000 × for 10 min) from fasted rats contain about 4 times more phosphorylase phosphatase activity when the liver was homogenized in a hypotonic medium or frozen before homogenization. This increase is caused by: (i) release of partially latent phosphatases (r=60 000 and 45 000 in sucrose gradient centrifugation) from ruptured organelles; (ii) rapid activation of phosphatase in the ruptured pellet by endogenous protease(s) which can be blocked by p-tosyl-L-lysine chloromethyl ketone. Only the r=60 000 enzyme, associated with the nuclei, can be activated proteolytically, with conversion to an r=45 000. 相似文献
14.
André Vandermeers Patrick Robberecht Marie-Claire Vandermeers-Piret Jean Rathé Jean Christophe 《Biochemical and biophysical research communications》1978,84(4):1076-1081
The interaction of a calcium-dependent regulator protein (CDR) of brain adenylate cyclase (EC 4.6.1.1) with synaptic membranes from guinea pig brain was examined using 125I-CDR as a tracer molecule. 125I-CDR binding was reversible, saturable, and temperature sensitive. The same Ca2+ and Mg2+ dependence was observed for 125I-CDR binding and for brain adenylate cyclase activation by CDR. 相似文献
15.
B D Howard 《Biochemical and biophysical research communications》1975,67(1):58-65
Mitochondria prepared from tissue that had been incubated with β-bungarotoxin exhibited abnormal respiration. The respiratory rate in the presence of substrate only was apparently normal, but it did not increase upon the addition of ADP. This effect could also be obtained by treatment with phospholipase A or oleate. Treatment with lesser amounts of these agents caused the mitochondria to become uncoupled. 相似文献
16.
K Seamon 《Biochemical and biophysical research communications》1979,86(4):1256-1265
The 250MHz NMR spectrum of the brain Ca2+-dependent regulator protein was examined in the absence of cations and in the presence of Ca2+ or Mg2+. The Ca2+-saturated regulator protein and Mg2+-saturated regulator protein exhibited several spectral differences in the aromatic and aliphatic regions of their spectra. Certain spectral changes observed to occur upon addition of metal ions are qualitatively similar to those which have been observed in the spectrum of skeletal troponin-C. These results suggest that the large sequence homology between skeletal troponin-C and the regulator protein results in similar conformational changes due to the binding of Ca2+ or Mg2+. 相似文献
17.
Disassembly of microtubules by the action of calmodulin-dependent protein kinase (Kinase II) which occurs only in the brain tissues 总被引:8,自引:0,他引:8
Microtubules assembled by the incubation of GTP at 37 °C were disassembled by the action of calmodulin-dependent protein kinase (Kinase II) which occrs only in the brain tissues. This disassembly required the presence of ATP and physiological concentrations of Ca2+ and calmodulin. 相似文献
18.
K Folkers T Kubiak H Stepien N Sakura 《Biochemical and biophysical research communications》1980,97(2):601-606
A new approach to the study of the molecular arrangements of proteins in membranes is described. Irradiation with visible light of native erythrocytes or washed erythrocyte membranes suspended in buffers containing a) riboflavin, fluorescein or fluorescein coupled to dextran and b) 3H-labelled tryptophan resulted in incorporation of radioactivity into the membrane proteins. Polyacrylamide gel electrophoresis of solubilized membranes followed by radioactivity measurements of the separated membrane proteins revealed that in native erythrocytes the protein components known to be located at the exterior cell surface, Band 3 and the major sialoglycoproteins became specifically labelled, whereas in washed lysed cells all of the major membrane proteins were labelled. 相似文献
19.
When human spermatozoa are extracted in the presence of 0.05 M benzamidine, the resulting solutions show a time dependent, sigmoidal increase of trypsin-like activity upon incubation at pH 8. Gel permeation chromatography of these extracts separates two species, P1 and P2, with apparent molecular weights of 75,000 and 42,000 respectively. P1 and P2 are both autoactivatable at pH 7–8 and the kinetic parameters of activated P1 and P2 are indistinguishable from those of human acrosin. That P1 and P2 are inactive precursors of human acrosin is shown by the fact that, in the presence of benzamidine, they are obtained instead of and in greater yield than acrosin. That P1 and P2 are zymogens is shown by the features of the activation process. 相似文献
20.
Isolated myosin light chain from chicken gizzard has been shown to serve as a substrate for Ca2+-activated phospholipid-dependent protein kinase. Autoradiography showed that Ca2+-activated phospholipid-dependent protein kinase phosphorylated mainly the 20,000-dalton light chain of chicken gizzard myosin. Exogenously added calmodulin had no effect on myosin light chain phosphorylation catalyzed by the enzyme. The 20,000-dalton myosin light chain, both in the isolated form and in the whole myosin form, served as the substrate for this enzyme. In contrast to the isolated myosin light chain, the light chain of whole myosin was phosphorylated to a lesser extent by the Ca2+-activated phospholipid dependent kinase. Our results suggest the involvement of phospholipid in regulating Ca2+-dependent phosphorylation of the 20,000-dalton light chain of smooth muscle myosin. 相似文献