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101.
Carina Modig Elisabeth Strömberg Margareta Wallin 《Molecular and cellular biochemistry》1994,130(2):137-147
Microtubule proteins were isolated by a temperature-dependent assembly-disassembly method from brain tissue of for cold-temperate fish; one fresh water fish (Oncorhynchus mykiss), and three marine fish (Labrus berggylta, Zoarces viviparus andGadus morhua). The -tubulins from all four fish species were acetylated. The -tubulins from the marine fish were composed of a mixture of tyrosinated and detyrosinated tubulin, while the fresh water fish tubulin only reacted with an antibody against detyrosinated tubulin. The isolated microtubules had a similar MAP composition. A 400 kD protein and a MAP2-like protein were found, but MAP1 was missing. All microtubules disassembled upon cooling to 0°C. In spite of these common characteristics, the assembly of microtubules fromLabrus berggylta was inhibited by colchicine and calcium, in contrast to the assembly of microtubules fromOncorhynchus mykiss andZoarces viviparus. For the latter, colchicine was not completely inhibitory even at a concentration as high as 1 mM, and calcium induced the formation of both loosely and densely coiled ribbons. The effects of calcium and colchicine on microtubules fromOncorhynchus mykiss andZoarces viviparus were modulated by either fish or cow MAPs, indicating that the effects are due to intrinsic properties of the fish tubulins and not the MAPs. In view of these findings, our results suggest that there is not correlation between colchicine sensitivity, inability of calcium to inhibit microtubule assembly, and acetylation and detyrosination. 相似文献
102.
Abstract— The Mg- and Ca-ATPase activities in a brain tubulin preparation have been measured. The activity of the microtubule protein (MTP) preparation was optimal, 3-4.5 nmol Pi/mg protein/min, at pH 8.0 in the presence of 1-2 m m -Mg2+ or Ca2+ , with a half maximal stimulation at about 0.3 m m concentration of either of the divalent ions.
Phosphocellulose (PC) purified tubulin exhibited no or very low activity (0-2 nmol Pi/mg protein/min).
The majority of ATPase activity was found in the microtubule associated proteins (MAP) fraction. It was stimulated by Mg2+ and Ca2+ , inhibited by NaF or high ionic strength but unaffected by vanadate at 10−4 m . In decreasing order of effectiveness ATP, GTP, UTP, CTP and ADP were hydrolyzed. p -Npp was a poor substrate. Vmax values for Mg- and Ca-ATPase activities were about 15 and 10 nmol Pi/mg protein/min, respectively with a Km value of about 25 μ m . However, double reciprocal plots disclosed more complicated kinetics, which were not fully resolved.
The activity was largely confined to 30-36S material (i.e.'rings'and 'spirals'). The protein responsible for the ATPase activity is possibly the smaller one of the two (or three) high molecular weight (HMW) proteins of mol wt over 200,000.
There are similarities between this enzyme and both flagellar dynein and myosin. However, the present ATPase differs from myosin in several important aspects (i.e. ionic requirements). Furthermore, no peptides of the myosin type were found upon electrophoretic analysis of the MAP fraction. 相似文献
Phosphocellulose (PC) purified tubulin exhibited no or very low activity (0-2 nmol Pi/mg protein/min).
The majority of ATPase activity was found in the microtubule associated proteins (MAP) fraction. It was stimulated by Mg
The activity was largely confined to 30-36S material (i.e.'rings'and 'spirals'). The protein responsible for the ATPase activity is possibly the smaller one of the two (or three) high molecular weight (HMW) proteins of mol wt over 200,000.
There are similarities between this enzyme and both flagellar dynein and myosin. However, the present ATPase differs from myosin in several important aspects (i.e. ionic requirements). Furthermore, no peptides of the myosin type were found upon electrophoretic analysis of the MAP fraction. 相似文献
103.
The activity of microsomal glutathione transferase was increased 1.7-fold in rat liver microsomes which carried out NADPH dependent metabolism of phenol. Known phenol metabolites were therefore tested for their ability to activate the microsomal glutathione transferase. The phenol metabolites benzoquinone and 1,2,4-benzenetriol both activated the glutathione transferase in microsomes 2-fold independently of added NADPH. However, NADPH was required to activate the enzyme in the presence of hydroquinone. Catechol did not activate the enzyme in microsomes. The purified enzyme was activated 6-fold and 8-fold by 5 mM benzenetriol and benzoquinone respectively. Phenol, catechol or hydroquinone had no effect on the purified enzyme. When microsomal proteins that had metabolized [14C]phenol were examined by SDS polyacrylamide gel electrophoresis and fluorography it was found that metabolites had bound covalently to a protein which comigrated with the microsomal glutathione transferase enzyme. We therefore suggest that reactive metabolites of phenol activate the enzyme by covalent modification. It is discussed whether the binding and activation has general implications in the regulation of microsomal glutathione transferase and, since some reactive metabolites might be substrates for the enzyme, their elimination through conjugation. 相似文献
104.
L C McPhail K A Waite D S Regier J B Nixon D Qualliotine-Mann W X Zhang R Wallin S Sergeant 《Biochimica et biophysica acta》1999,1439(2):277-290
Activation of phospholipase D occurs in response to a wide variety of hormones, growth factors, and other extracellular signals. The initial product of phospholipase D, phosphatidic acid (PA), is thought to serve a signaling function, but the intracellular targets for this lipid second messenger are not clearly identified. The production of PA in human neutrophils is closely correlated with the activation of NADPH oxidase, the enzyme responsible for the respiratory burst. We have developed a cell-free system, in which the activation of NADPH oxidase is induced by the addition of PA. Characterization of this system revealed that a multi-functional cytosolic protein kinase was a target for PA, and that two NADPH oxidase components were substrates for the enzyme. Partial purification of the PA-activated protein kinase separated the enzyme from known protein kinase targets of PA. The partially purified enzyme was selectively activated by PA, compared to other phospholipids, and phosphorylated the oxidase component p47-phox on both serine and tyrosine residues. PA-activated protein kinase activity was present in a variety of hematopoietic cells and cell lines and in rat brain, suggesting it has widespread distribution. We conclude that this protein kinase may be a novel target for the second messenger function of PA. 相似文献
105.
Wallin H 《Mutation research》2000,447(2):317-318
106.
Johanna Deinum Margareta Wallin Martin Kanje Carl Lagercrantz 《Biochimica et Biophysica Acta (BBA)/General Subjects》1981,675(2):209-213
The assembly of microtubules was found to decrease in proportion to the amount of added ruthenium red, indicating a high affinity of ruthenium red for the microtubule system. An equimolar amount of ruthenium red per tubulin dimer inhibited the microtubule assembly completely and disassembled existing microtubules. Binding of ruthenium red to tubulin is accompanied by a shift in the absorption maximum from 535 to 538 nm. The binding is very strong, as shown by the finding that ruthenium red could not be displaced from tubulin by gel chromatography on Sephadex, or by the addition of Ca2+ or Mg2+. The binding of ruthenium red to tubulin did not affect the single colchicine site, nor the Mg2+ site(s), as shown by use of Mn2+ as an EPR probe. Ruthenium red also interfered with microtubules in an intact cell system, as it inhibited rapid axonal transport in the frog sciatic nerve, measured by the accumulation of [3H]leucine-labelled proteins in front of a ligature. 相似文献
107.
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110.
Ann?BrinkmalmEmail author Gunnar?Brinkmalm William?G?Honer Lutz?Fr?lich Lucrezia?Hausner Lennart?Minthon Oskar?Hansson Anders?Wallin Henrik?Zetterberg Kaj?Blennow Annika??hrfelt 《Molecular neurodegeneration》2014,9(1):53