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91.
Kritsky MS Telegina TA Vechtomova YL Kolesnikov MP Lyudnikova TA Golub OA 《Biochemistry. Biokhimii?a》2010,75(10):1200-1216
Excited flavin and pterin molecules are active in intermolecular energy transfer and in photocatalysis of redox reactions
resulting in conservation of free energy. Flavin-containing pigments produced in models of the prebiotic environment are capable
of converting photon energy into the energy of phosphoanhydride bonds of ATP. However, during evolution photochemical reactions
involving excited FMN or FAD molecules failed to become participants of bioenergy transfer systems, but they appear in enzymes
responsible for repair of UV-damaged DNA (DNA photolyases) and also in receptors of blue and UV-A light regulating vital functions
of organisms. The families of these photoproteins (DNA-photolyases and cryptochromes, LOV-domain- and BLUF-domain-containing
proteins) are different in the structure and in mechanisms of the photoprocesses. The excited flavin molecules are involved
in photochemical processes in reaction centers of these photoproteins. In DNA photolyases and cryptochromes the excitation
energy on the reaction center flavin is supplied from an antenna molecule that is bound with the same polypeptide. The role
of antenna is played by MTHF or by 8-HDF in some DNA photolyases, i.e. also by molecules with known coenzyme functions in
biocatalysis. Differences in the structure of chromophore-binding domains suggest an independent origin of the photoprotein
families. The analysis of structure and properties of coenzyme molecules reveals some specific features that were significant
in evolution for their being selected as chromophores in these proteins. 相似文献
92.
Sherin Antony Peeyush Kumar T Jobin Mathew TR Anju CS Paulose 《Journal of biomedical science》2010,17(1):7
Glucose homeostasis in humans is an important factor for the functioning of nervous system. Hypoglycemia and hyperglycemia is found to be associated with central and peripheral nerve system dysfunction. Changes in acetylcholine receptors have been implicated in the pathophysiology of many major diseases of the central nervous system (CNS). In the present study we showed the effects of insulin induced hypoglycemia and streptozotocin induced diabetes on the cerebellar cholinergic receptors, GLUT3 and muscle cholinergic activity. Results showed enhanced binding parameters and gene expression of Muscarinic M1, M3 receptor subtypes in cerebellum of diabetic (D) and hypoglycemic group (D + IIH and C + IIH). α7nAchR gene expression showed a significant upregulation in diabetic group and showed further upregulated expression in both D + IIH and C + IIH group. AchE expression significantly upregulated in hypoglycemic and diabetic group. ChAT showed downregulation and GLUT3 expression showed a significant upregulation in D + IIH and C + IIH and diabetic group. AchE activity enhanced in the muscle of hypoglycemic and diabetic rats. Our studies demonstrated a functional disturbance in the neuronal glucose transporter GLUT3 in the cerebellum during insulin induced hypoglycemia in diabetic rats. Altered expression of muscarinic M1, M3 and α7nAchR and increased muscle AchE activity in hypoglycemic rats in cerebellum is suggested to cause cognitive and motor dysfunction. Hypoglycemia induced changes in ChAT and AchE gene expression is suggested to cause impaired acetycholine metabolism in the cerebellum. Cerebellar dysfunction is associated with seizure generation, motor deficits and memory impairment. The results shows that cerebellar cholinergic neurotransmission is impaired during hyperglycemia and hypoglycemia and the hypoglycemia is causing more prominent imbalance in cholinergic neurotransmission which is suggested to be a cause of cerebellar dysfunction associated with hypoglycemia. 相似文献
93.
94.
A mechanism of cyclin D1 action encoded in the patterns of gene expression in human cancer 总被引:33,自引:0,他引:33
Lamb J Ramaswamy S Ford HL Contreras B Martinez RV Kittrell FS Zahnow CA Patterson N Golub TR Ewen ME 《Cell》2003,114(3):323-334
95.
Nontemplate (N)-nucleotide addition by the terminal dideoxynucleotidyl transferase (TdT) at the junctions of rearranging V(D)J gene segments greatly contribute to antigen-receptor diversity. TdT has been identified in several vertebrate species, where it is highly conserved. We report here the isolation of two forms of TdT mRNA in an amphibian, the Mexican axolotl. The isoform TdT1 shares all of the conserved structural motifs required for TdT activity and displays an average of 50–58% similarity at the amino acid level with TdT of other species. The second axolotl TdT variant (TdT2) differs from TdT1 by a 57-amino acid deletion located between amino acids 165–222 of TdT1, including the first helix–hairpin–helix DNA-binding motif. During ontogeny, TdT products are first detected in the head of 6-week-old larvae and further in the head and trunk of 8-month-old larvae. These developmental stages correspond to the first detection of RAG1 and antigen-receptor (TCR and IgH) products in axolotl larvae. Our results suggest that in contrast to mammalian development, N diversity occurs early in axolotl development to diversify the primary repertoire. Phylogenetic analyses reveal that TdT and DNA polymerase (Pol ) genes are closely related, and that both enzymes were already present in the common ancestor of jawed vertebrates.This work is dedicated to the memory of Prof. Jacques CharlemagneThe sequences reported in this paper have been deposited in the GenBank database (accession numbers AF039209 and AY248700) 相似文献
96.
Gamma interferon triggers interaction between ICSBP (IRF-8) and TEL,recruiting the histone deacetylase HDAC3 to the interferon-responsive element 下载免费PDF全文
Kuwata T Gongora C Kanno Y Sakaguchi K Tamura T Kanno T Basrur V Martinez R Appella E Golub T Ozato K 《Molecular and cellular biology》2002,22(21):7439-7448
97.
Kirsch T Koyama E Liu M Golub EE Pacifici M 《The Journal of biological chemistry》2002,277(44):42171-42177
Chondrocyte proliferation is important for skeletal development and growth, but the mechanisms regulating it are not completely clear. Previously, we showed that syndecan-3, a cell surface heparan sulfate proteoglycan, is expressed by proliferating chondrocytes in vivo and that proliferation of cultured chondrocytes in vitro is sensitive to heparitinase treatment. To further establish the link between syndecan-3 and chondrocyte proliferation, additional studies were carried out in vivo and in vitro. We found that the topographical location of proliferating chondrocytes in developing chick long bones changes with increasing embryonic age and that syndecan-3 gene expression changes in a comparable manner. For in vitro analysis, mitotically quiescent chondrocytes were exposed to increasing amounts of fibroblast growth factor-2 (FGF-2). Proliferation was stimulated by as much as 8-10-fold within 24 h; strikingly, this stimulation was significantly prevented when the cells were treated with both fibroblast growth factor-2 (FGF-2) and antibodies against syndecan-3 core protein. This neutralizing effect was dose-dependent and elicited a maximum of 50-60% inhibition. To establish specificity of neutralizing effect, cultured chondrocytes were exposed to FGF-2, insulin-like growth factor-1, or parathyroid hormone, all known mitogens for chondrocytes. The syndecan-3 antibodies interfered only with FGF-2 mitogenic action, but not that of insulin-like growth factor-1 or parathyroid hormone. Protein cross-linking experiments indicated that syndecan-3 is present in monomeric, dimeric, and oligomeric forms on the chondrocyte surface. In addition, molecular modeling indicated that contiguous syndecan-3 molecules might form stable complexes by parallel pairing of beta-sheet segments within the ectodomain of the core protein. In conclusion, the results suggest that syndecan-3 is a direct and selective regulator of the mitotic behavior of chondrocytes and its role may involve formation of dimeric/oligomeric structures on their cell surface. 相似文献
98.
Golub AS Pittman RN 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2002,132(1):169-176
Work by previous investigators has indicated that a substantial amount of oxygen diffuses from the precapillary circulation. These losses imply that there should be radial gradients of oxygen tension (PO(2)) in arterioles, leading to a non-uniform distribution of oxygen within these microvessels. We have employed the phosphorescence quenching method to measure oxygen, allowing us to evaluate the heterogeneity of PO(2) inside short segments of microvessels. The phosphorescence decay curve contains information about the distribution of oxygen within the excited volume and the distribution can be represented as a histogram, by decomposing the decay curve into several components with weights proportional to the volume fraction of plasma with different PO(2), under the condition of a high signal-to-noise ratio. Furthermore, the histogram can be converted into a radial profile of PO(2), based on the assumptions of a circular vascular lumen, axisymmetric distribution of oxygen and monotonic PO(2) profile. Albumin-bound Pd-porphyrin phosphor was infused into the circulation of hamsters and excited by flash illumination at 10 Hz, with a square region of excitation light just covering the entire lumen, (i.e. width of region equaled luminal diameter) of microvessels in the hamster mesentery. A set of 50 curves (5 s of data) was averaged to obtain a decay curve with low noise. Curves were analyzed with the above histogram procedure, and this analysis allowed us to distinguish between PO(2) values originating from intra and extravascular subvolumes. The intravascular PO(2) in these microvessels was very heterogeneous, which could be explained by the existence of significant radial PO(2) gradients. The radial PO(2) gradients were estimated to be approximately 1 mmHg/microm. 相似文献
99.
Bcl2 regulation by the melanocyte master regulator Mitf modulates lineage survival and melanoma cell viability 总被引:25,自引:0,他引:25
100.