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181.
Mikio Yoshidomi Takashi Hayashi Koji Abe Kyuya Kogure 《Journal of neurochemistry》1989,53(5):1589-1594
The effects of a new calcium channel blocker, 1-[bis(4-fluorophenyl)methyl]-4-(2,3,4-trimethoxybenzyl)-piperazine dihydrochloride (KB-2796), on delayed neuronal death (DND) in the hippocampus were examined in gerbils in comparison with those of pentobarbital and flunarizine. The neuronal density in the hippocampal CA1 subfield was counted on the seventh day of recirculation following 5 min of bilateral carotid occlusion, and protein biosynthesis in the brain was also determined at 1, 2, 4, 24, and 72 h following occlusion. The drugs were intraperitoneally administered after recirculation. KB-2796 (10 mg/kg) significantly prevented DND in the CA1 subfield. Pentobarbital (40 mg/kg), but not flunarizine (3 and 10 mg/kg), inhibited DND. Protein synthetic activity in the CA1 subfield was reduced by ischemia and the reduction was not restored even at 72 h after recirculation. KB-2796 did not ameliorate the reduction of protein synthesis in the CA1 subfield by 24 h after recirculation, but in one of three animals restoration of protein synthesis was observed at 72 h of recirculation. Pentobarbital also restored the reduced protein synthesis in two of three animals at 72 h. These results suggest that calcium influx into neurons participates in the pathogenesis of DND, and also that KB-2796 might prevent both morphological and functional cell damage in CA1 neurons induced by transient ischemia. 相似文献
182.
183.
Chymotrypsin inhibitor-2, a lysine-rich protein in the barley endosperm, has been localized at the ultrastructural level by immunocytochemistry in developing barley endosperm cells 14 days post anthesis. The protein is deposited in the protein bodies. Two morphologically distinct types of protein bodies, small spherical and large irregularly shaped, are present. Golgi-apparatus-derived vesicles whose content is labelled by chymotrypsin inhibitor-2 antibody-gold particles are observed at the Golgi complex and around the vacuoles. These observations indicate that the transport of the protein to the site of deposition is mediated by the Golgi apparatus.Abbreviations CI
chymotrypsin inhibitor
- DPA
days post anthesis
- ER
endoplasmic reticulum
The authors wish to thank Dr. V.R. Franceschi (Department of Botany, Washington State University, Pullman, USA) for many helpful discussions and advice during the work, and the staff at the Electron Microscope Center at Washington State University for technical assistance. 相似文献
184.
Summary The short-term effects of NaCl and mannitol stress on plasma membrane (PM) polypeptides from corn roots (Zea mays L.) were determined using two-dimensional gel electrophoresis following radiolabeled amino acid incorporation. After 2.5 hours, both stress treatments altered synthesis of several polypeptides. Changes included up-regulation of some polypeptides with concomitant down-regulation of others. Some changes were unique to the stress treatment while others were common to both NaCl and mannitol. No new polypeptides appeared in either case. Pulse-chase experiments following 0.5-hours and 2.5-hours incubation periods with radiolabeled amino acids did not reveal differences in turnover of PM polypeptides. The results support the contention that altered synthesis of PM proteins under stress may contribute to the alteration of membrane function.Abbreviations ER
endoplasmic reticulum: GA Golgi
- PM
plasma membrane
- PVPP
polyvinylpolypyrrolidone 相似文献
185.
S. Romagnoli M. Maddaloni C. Livini M. Motto 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1990,80(6):769-775
Summary To provide an insight into the molecular basis of heterosis, we investigated gene expression in primary root tips of a heterotic maize hybrid (B73 × Mo17) and its parental lines (B73 and Mo17). This analysis was carried out (i) by differential plaque hybridization of a recombinant cDNA library made to poly(A) RNA isolated from B73 × Mo17 primary root tips, and (ii) by comparing with two-dimensional gel electrophoresis proteins synthesized in vitro in the rabbit reticulocyte system by poly(A) RNA isolated, at different stages of development, from the three genotypes. The results showed that there are sets of proteins and mRNAs that are differentially synthesized and expressed in the F1 primary root tips in comparison to the parental lines. Moreover, results from the survey of 21 major in-vitrosynthesized polypeptide variants, from mRNAs of primary root tips of the parental lines and their F1 hybrid, indicated that in seven instances hybrid proteins translated in vitro were more abundant or possibly new. In most of the remaining cases, hybrid spots were similar in intensity to the same protein produced by one of the two parental lines. 相似文献
186.
Sorbitol dehydrogenase (EC 1.1.1.14) was isolated from bovine brain and purified 3,000-fold to apparent homogeneity, as judged by polyacrylamide gel electrophoresis. The purified enzyme had a specific activity of 36 units/mg of protein; a molecular weight of 39,000 for each of the four identical subunits and 155,000 for the intact enzyme were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel exclusion chromatography, respectively. The presence of one Zn2+ per subunit was confirmed by atom absorption spectroscopy; inactivation of the enzyme by metal-chelating agents points to the essential role that Zn2+ plays in the catalytically competent enzyme. The enzyme is also inactivated by thiol-blocking reagents; with respect to inactivation by sodium pyrophosphate, sorbitol dehydrogenase is different from closely related alcohol dehydrogenase. 相似文献
187.
Forskolin, an activator of adenylate cyclase, stimulates adrenocorticotropin (ACTH) release and increases proopiomelanocortin mRNA levels in anterior pituitary cells by enhancing cyclic AMP (cAMP)-dependent protein kinase activity. The phorbol ester phorbol 12-myristate 13-acetate (PMA) evokes these same responses from anterior pituitary cells by activating protein kinase C. Both protein kinases most likely induce their cellular effects by catalyzing the phosphorylation of specific proteins. To elucidate the mechanisms by which cAMP-dependent protein kinase and protein kinase C promote ACTH secretion and synthesis, the phosphoproteins regulated by forskolin and PMA were identified in the cell line AtT-20, which consists of a homogeneous population of corticotrophs. Phosphoproteins were analyzed in different subcellular fractions by two-dimensional polyacrylamide gel electrophoresis and autoradiography. Forskolin increased phosphate incorporation into two proteins in the cytoplasmic fraction of 24 kilodaltons (kd) (pI 6.8) and 40 kd (pI 5.8), two proteins in the plasma membrane fraction of 32 kd (pI 8.3) and 60 kd (pI 8), and one protein in the nuclear fraction of 20 kd (pI 8.7). Insertion of the inhibitor of cAMP-dependent protein kinase into the AtT-20 cells, using a liposome technique, blocked the rise in phosphate incorporation induced by forskolin. PMA also stimulated phosphate incorporation into proteins in AtT-20 cells. PMA increased the phosphorylation of three cytoplasmic proteins of 25 kd (pI 7.6), 40 kd (pI 5.8), and 40 kd (pI 8.1) as well as two membrane proteins of 32 kd (pI 8.3) and 60 kd (pI 8) and one nuclear protein of 20 kd (pI 6.3).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
188.
Recent years have seen the convergence of both genetic and biochemical approaches in the study of protein translocation inE. coli. The powerful combination of these approaches is exemplified in the use of anin vitro protein synthesis-protein translocaltion system to analyze the role of genetically defined components of the protein translocation machinery. We describe in this review recent results focusing on the function of thesecA, secB, andsecY gene products and the demonstration of their requirement forin vitro protein translocation. The SecA protein was recently shown to possess ATPase activity and was proposed to be a component of the translocation ATPase. We present a speculative working model whereby the translocator complex is composed of the integral membrane proteins SecY, SecD, SecE, and SecF, forming an aqueous channel in the cytoplasmic membrane, and the tightly associated peripheral membrane protein SecA functioning as the catalytic subunit of the translocator or protein-ATPase. 相似文献
189.
Techel D. Gebauer G. Kohler W. Braumann T. Jastorff B. Rensing L. 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1990,159(6):695-706
Summary Pulses of some Ca2+ channel blockers (dantrolene, Co2+, nifedipine) and calmodulin inhibitors (chlorpromazine) lead to medium (maximally 5–9 h) phase shifts of the circadian conidiation rhythm ofNeurospora crassa. Pulses of high Ca2+, or of low Ca2+, a Ca2+ ionophore (A23187) together with Ca2+, and other Ca2+ channel blockers (La3+, diltiazem), however, caused only minor phase shifts. The effect of these substances (A 23187) and of different temperatures on the Ca2+ release from isolated vacuoles was analyzed by using the fluorescent dye Fura-2. A 23187 and higher temperatures increased the release drastically, whereas dantrolene decreased the permeation of Ca2+ (Cornelius et al., 1989).Pulses of 8-PCTP-cAMP, IBMX and of the cAMP antagonist RP-cAMPS, also caused medium (maximally 6–9 h) phase shifts of the conidiation rhythm. The phase response curve of the agonist was almost 180° out of phase with the antagonist PRC. In spite of some variability in the PRCs of these series of experiments all showed maximal shifts during ct 0–12. The variability of the response may be due to circadian changes in the activity of phosphodiesterases: After adding cAMP to mycelial extracts HPLC analysis of cAMP metabolites showed significant differences during a circadian period with a maximum at ct 0.Protein phosphorylation was tested mainly in an in vitro phosphorylation system (with35S-thio -ATP). The results showed circadian rhythmic changes predominantly in proteins of 47/48 kDa. Substances and treatments causing phase-shifts of the conidiation rhythm also caused changes in the phosphorylation of these proteins: an increase was observed when Ca2+ or cAMP were added, whereas a decrease occurred upon addition of a calmodulin inhibitor (TFP) or pretreatment of the mycelia with higher (42° C) temperatures.Altogether, the results indicate that Ca2+-calmodulin-dependent and cAMP-dependent processes play an important, but perhaps not essential, role in the clock mechanism ofNeurospora. Ca2+ calmodulin and the phosphorylation state of the 47/48-kDa proteins may have controlling or essential functions for this mechanism. 相似文献
190.