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131.
132.
The 125I-labeled Mr 80000 form of neurophysin has been purified from bovine neurohypophysi. Tryptic digests of this species were analyzed, prior to or after treatment with carboxypeptidase B, by high-pressure liquid chromatography followed by isoelectric focusing and the fragments compared with those generated by a similar treatment of reference bovine 1-39 adrenocorticotropin. The ACTH peptides 22-39 and 1-8, as well as the 1-7 derivative of the latter were identified by those two independent criteria. This provides chemical evidence supporting the hypothesis [8] that high Mr neurophysin may contain the sequence of ACTH. 相似文献
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ATP promotes 45Ca uptake by the microsomal fraction from the longitudinal smooth muscle of guinea-pig ileum and this uptake is stimulated by oxalate. As the microsomal fraction is made up of various subcellular entities, we examined the localization of the Ca2+-transport activity by density gradient centrifugation, taking advantage of the selective effect of digitonin (at low concentration) on the density of plasmalemmal elements. When the 45Ca-uptake activity was measured in the absence of oxalate, its behavior in subfractionation experiments closely paralleled that of the plasmalemmal marker 5′-nucleotidase. In contrast, the additional Ca2+-transport activity elicited by oxalate behaved like NADH-cytochrome reductase, a putative endoplasmic reticulum marker. The endoplasmic reticulum vesicles constituted only a small part of the membranes in the microsomal fraction, which explains that their Ca2+-storage capacity was not detectable in the absence of Ca2+-trapping agent. Low digitonin concentrations selectively increased the Ca2+ permeability of the plasmalemmal vesicles. The two Ca2+-transport activities were further differentiated by their distinct sensitivities to K+, vanadate and calmodulin. In this respect, the oxalte-insensitive and oxalate-stimulated Ca2+-transport systems resembled, respectively, the sarcolemmal and sarcoplasmic reticulum Ca2+ pumps in cardiac and skeletal muscle, in accordance with the subcellular locations established by density gradient centrifugation. 相似文献
138.
Grard Morel Paul Dubois Claudine Benassayag Emmanuel Nunez Christine Radanyi Grard Redeuilh Hlne Richard-Foy Etienne-Emile Baulieu 《Experimental cell research》1981,132(2):249-257
Antiserum against calf uterus oestradiol receptor has been used for detecting oestradiol receptor in rat pituitary cells at the ultrastructural level after immunochemical reaction according to Sternberger. The gonadotropic, lactotropic and somatotropic cells were positive, but not the thyrotropic and corticotropic cells. In peripubertal and adult rats, both cytoplasmic and nuclear receptors were seen, but in a long-term castrated rat, the receptor was found only in the cytoplasm. After oestradiol administration to 21-day-old animals, the cytoplasmic receptor decreased and the nuclear receptor increased in gonadotropic cells, supporting the concept of hormone-receptor complex translocation. Antibodies against α1-foetoprotein demonstrated the presence of this oestrogen-binding plasma protein in all pituitary cells, but only in the cytoplasmic area. These results and the immunological controls related to antibody specificity give the first evidence of steroid receptor at the ultrastructural level. 相似文献
139.
Experiments have been undertaken to correlate physiological changes, observed in two YC8 cells variants (P and L) and some of their immunological and enzymatic properties. These cell lines show different responses towards antilymphocyte and anti-Moloney sera. Subcellular fractionations have been made. The A fractions (d: 1.14/1.16) have the highest ouabain-inhibited Mg2+-stimulated (Na+-K+)-dependent ATPase and galactosyltransferase activities. Some properties of the latter enzyme have been studied: whereas optima pH and requirements for Mn2+ ions have been found to be the same for both cell line enzymes, on the contrary, different kinetic parameters have been shown with respect to sugar donor (UDP-galactose) on endogeneous or exogeneous (ovomucoid) acceptors. Apparent Km for UDP-galactose is 1.7 × 10−6 M (P-cells) and 3.3 × 10−6 M (L-cells), on endogeneous acceptors, and P-cell V max < L-cell V max; on ovomucoid it is 0.61 × 10−6 M, for both cell lines. These results suggest the presence on L-cells of more endogeneous acceptor sites, the higher affinity of P-cells for UDP-galactose being balanced by less endogeneous acceptor sites for galactose. When ovomucoid is added, galactose transfer on endogeneous acceptor sites of both cells is negligible. Apparent Km for ovomucoid is 8.6 × 10−5 M (P-cells) and 4.3 × 10−5 M (L-cells). These data support the above-mentioned hypothesis: L-cell enzymes would be more rapidly saturated than P-cell enzymes because of the higher number of endogeneous sites on L-cells.This supposed acquired character of L-cells as well as their immunological behaviour could explain the modified properties of L-cells as compared to P-cells. 相似文献
140.
G. Morel 《Journal of invertebrate pathology》1976,28(2):167-175
An endemic disease caused by an intracellular microorganism related to the Chlamydiales, Porochlamydia buthi g. n., sp. n., exists in populations of the scorpion Buthus occitanus of Languedoc in southern France. The pathogen's developmental cycle occurs in the hepatopancreatic cells and progressively brings about the destruction of this organ. The microorganism is spread mostly through dejecta which contain the infectious forms during nearly the entire period of illness. 相似文献