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41.
Properties and characterization of a highly purified sarcoplasmic reticulum Ca2+-ATPase from dog cardiac and rabbit skeletal muscle 总被引:1,自引:0,他引:1
Sarcoplasmic reticulum (SR) Ca2+-ATPase was purified from dog cardiac and rabbit skeletal muscle using Triton X-100 at optimal ratios of 0.5 for cardiac and 0.5 to 1.0 for skeletal SR. The yields of Ca2+-ATPase were 4 to 5 and 1 to 2.2 mg/100 mg of cardiac and skeletal SR protein, respectively. The enzyme activities were 547 +/- 67 mumol ADP/mg/h for cardiac and 1192 +/- 172 mumol ADP/mg/h for skeletal Ca2+-ATPase. Removal of excess Triton X-100 increased the enzyme activities to 719 +/- 70 and 1473 +/- 206 mumol ADP/mg/h, respectively. The residual content of Triton X-100 for cardiac and skeletal Ca2+-ATPase was 20 and 5 mol/mol of enzyme, respectively. Maximum levels of phosphoenzyme were 4.4 +/- 0.2 and 5.6 +/- 0.6 nmol/mg in each case. A single protein band of 100 kDa was obtained for each purified Ca2+-ATPase by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The preparations were stable at -80 degrees C for 5 months in the presence of 1 mM Ca2+. The phospholipid content of the purified enzyme was 2-fold greater than that of native cardiac and skeletal SR microsomes. Repeated washing of the purified enzyme preparation did not alter the phospholipid content or the specific activities. 相似文献
42.
Heterogeneity of leukotriene receptors in guinea-pig trachea 总被引:7,自引:0,他引:7
The selective leukotriene (LT) antagonist FPL 55712 antagonized the contractile activity of synthetic LTD4 and E4 on guinea-pig trachea. Schild analysis of the antagonism provided evidence for two distinct receptors for LTD4: one with significantly higher affinity for FPL 55712 than the other. LTE4 appears to interact preferentially with the high affinity receptor. 相似文献
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44.
Two additional phosphorylases (III and IV) have been detected in developing seeds of maize. Phosphorylase IV is found only in the embryo (with scutellum). It is also present in the embryo of the germinating seed where its activity is 90-fold greater than the activity in the developing embryo 22 days after pollination. Phosphorylase IV is eluted from a DEAE-cellulose column in the same fraction as phosphorylase I of the endosperm, and the 2 enzymes are similar in many respects. Phosphorylase IV is distinguished from phosphorylase I by electrophoretic mobility, by pH optimum, and because its properties are not affected by the shrunken-4 mutation.Phosphorylase III is found both in the endosperms and embryos of developing seeds. Activity for this enzyme is not detected in crude homogenates nor eluates from a DEAE-cellulose column apparently because it complexes with a non-dialyzable, heat-labile inhibitor. High activity is found after protamine sulfate fractionation. Phosphorylase III is bound to protamine sulfate and is then removed by washing with 0.3 m phosphate buffer. Phosphorylase III activity in the endosperm is not detectable 8 days after pollination but is present 12 days after pollination. Phosphorylase III differs from phosphorylases I, II, and IV in several respects-pH optimum, pH-independent ATP inhibition, time of appearance in the endosperm, and because purine and pyrimidine nucleotides are equally inhibitory. In common with phosphorylase II, phosphorylase III apparently does not require a primer to initiate the synthesis of an amylose-like polymer. 相似文献
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47.
Human homologs of two testes-expressed loci on mouse chromosome 17 map to opposite arms of chromosome 6 总被引:3,自引:0,他引:3
K B Bibbins J Y Tsai J Schimenti N Sarvetnick H Y Zoghbi P Goodfellow L M Silver 《Genomics》1989,5(1):139-143
Our laboratory has recently cloned and characterized two testes-expressed loci--the Tcp-10 gene family cluster and the D17Si11 gene--that map to the proximal portion of mouse chromosome 17. Human homologs of both loci have been identified and cloned. Somatic cell hybrid lines have been used to map the human homolog of D17Si11 to the short arm of chromosome 6 (p11-p21.1) along with homologs of other genes from the (Pim-1)-(Pgk-2) region of the mouse chromosome. The human TCP 10 locus maps to the long arm of chromosome 6 (q21-qter) along with homologs of other genes from the mouse chromosome 17 region between the centromere and Pim-1. The mapping of large portions of the mouse t haplotype to unlinked regions on human chromosome 6 rules out the possibility that a t-haplotype-like chromosome could exist in humans. 相似文献
48.
Endocytosis in the retinal pigment epithelium (RPE) of rats was studied using horseradish peroxidase, microperoxidase and ferritin tracers. Tracer uptake was mediated by coated pits and coated vesicles. Coated pits formed at two discrete regions at the RPE plasma membrane: that portion of basal membrane directly opposing Bruch's membrane, and at the bases of the apical lamellae and villi. Two populations of coated vesicles were identified and distinguished by size, location and function. Large coated vesicles (91.8 +/- 14.7 nm in diameter) were located near the cell surface and incorporated tracer. Small coated vesicles (64.5 +/- 15.7 nm diameter) located more deeply within the cell were not tracer-labeled, and were often fused with the endoplasmic reticulum or the Golgi apparatus. Observations of the endocytic pathway in rat RPE cells are presented. Tracer was also found in organelles of the lysosomal system, e.g. the multivesicular body, but was not identified in the smooth endoplasmic reticulum or Golgi apparatus. 相似文献
49.
The pathologic aspects of 248 cases of amyloidosis in pigtailed macaques (Macaca nemestrina) at the Washington Regional Primate Research Center from 1971 through 1985 were studied. Amyloid was present in the spleen, liver and gastrointestinal (GI) tract, either alone or in combination, in nearly 75% of the monkeys. Its occurrence declined with age in the spleen and the GI tract, but increased with age in the liver. Both intestinal inflammation and retroperitoneal fibromatosis were strongly associated with amyloid deposition in the GI tract. Monkeys with histopathologic findings of enteritis or enterocolitis and glomerulonephritis were at increased risk of developing amyloidosis. Forty cases of amyloidosis with a history of chronic diarrhea had type AA amyloid by histochemical tests. 相似文献
50.
M M Slattum S L Rosenkranz R F DiGiacomo C C Tsai W E Giddens 《Laboratory animal science》1989,39(6):560-566
A retrospective study of amyloidosis in pigtailed macaques (Macaca nemestrina) at the Washington Regional Primate Research Center (WRPRC) was conducted. Between 1971 and 1985, 248 of 1,952 (13%) necropsies revealed amyloidosis in pigtailed macaques. The influence of demographic factors, diseases and experimental interventions on amyloidosis was examined. Univariate analyses, using two controls for each case, indicated that age, sex, birthplace and residence were related to amyloidosis. After adjusting for age, females were not at greater risk. However, monkeys born at the WRPRC were at greater risk and monkeys 0 to 5 years old residing at the breeding colony were at greater risk than monkeys at the research center. After adjustment for age, monkeys were at greater risk of developing amyloidosis if they had a history of episodes of diarrhea, respiratory disease or trauma. As the number of episodes increased, the risk increased. Monkeys with retroperitoneal fibromatosis, a manifestation of simian D retrovirus infection, were also at greater risk. Using logistic regression and controlling for age, sex, birthplace and residence, monkeys with diarrhea remained at an elevated risk for amyloidosis. Compared with a model combining diarrhea, respiratory disease, septicemia, surgery, trauma and retroperitoneal fibromatosis, a model with diarrhea alone accounted for most of the increased risk. 相似文献