共查询到20条相似文献，搜索用时 15 毫秒
1.
The structure of an invertebrate, intron-containing globin gene has been determined as part of a study of the evolution of hemoglobin. The gene encoding chain c of Lumbricus terrestris hemoglobin has the two-intron, three-exon structure characteristic of vertebrate globin genes, and the exact positions of the splice junctions are conserved. The two introns interrupting the coding sequence are longer than those of known hemoglobins but shorter than myoglobin introns. The gene encodes a secretory preglobin containing a 16-residue signal peptide, as expected for an extracellular hemoglobin. However, no intron separates the DNA encoding the signal sequence from that of the globin sequence. The 3' untranslated region of the Lumbricus gene is much longer than those of the genes for other hemoglobins and is similar to those found for myoglobins. 相似文献
2.
K Moffat 《Science (New York, N.Y.)》1974,185(147):274-277
The altered gelation behavior found in mixtures of sickle cell hemoglobin with other hemoglobins is due to the formation of hybrid hemoglobin tetramers from unlike dimers. The hemoglobins need not possess the deoxy quaternary structure for gelation to occur; liganded forms are also capable of participation in gelation. 相似文献
3.
Starch gel electrophoretic patterns of hemoglobins from fetal mice of seven inbred strains (two with single, five with diffuse adult hemoglobins), were compared with each other and with electrophoretic patterns of hemoglobins from adults of the same strains. The blood from 15-day-old fetuses of all strains contained four electrophoretically separable heme components. However, there seems to be a difference between strains with single and diffuse adult hemoglobin in the time of emergence of a clear adult pattern. 相似文献
4.
C Manwell 《Science (New York, N.Y.)》1966,152(727):1393-1396
The hemoglobin of the "thin" sibling species of Thyonella gemmata (phylum: Echinodermata; class: Holothuria) has three electrophoretically distinct polypeptide chains. In "stout" sibling species of T. gemmata there are only two chain types. These results account for the greater number of multiple hemoglobins in "thins" than in "stouts," as well as for differences in the amounts of some of the multiple hemoglobins when comparisons are mnade of hemolyzates of erythrocytes from the water vascular systemn and from the main body cavity of the "thin" but not the "stout" sibling species. 相似文献
5.
R Q Blackwell B N Blackwell J T Huang L C Chien A Samaharn C Thephusdin C Borvornsin 《Science (New York, N.Y.)》1965,150(703):1614-1615
Hemoglobin J(Korat), a "fast" hemoglobin with an anomaly in its beta chain different from the anomalies previously reported, was the major hemoglobin component in the blood of nine subjects among 1923 Thais from northeastern Thailand. After hemoglobin E, J(Korat) is the second most frequent of the anomalous hemoglobins among Thais. 相似文献
6.
In vivo studies of the biosynthesis of chick hemoglobins 1 and 2 showed an over-all higher incorporation of glycine-2-C(14), valine-4-C(14), valine-1-C(14), leucine-G-C(14), and histidine-(2-ring)-C(14) in hemoglobin 2; in vitro studies made with intact nucleated chick erythrocytes showed the higher incorporation of glycine-2-C(14), valine-1-C(14), and histidine-(2-ring)-C(14) in hemoglobin 1. Hybridization of chick hemoglobins produced an electrophoretically distinguishable new component. 相似文献
7.
In an examination of the blood of 708 Eskimos, 200 Aleuts, and 44 Indians in Alaska for abnormal types of hemoglobin, only normal hemoglobin A was detected. It may be concluded that abnormal hemoglobins in these races are rare if they occur at all. 相似文献
8.
对葡萄血红蛋白基因的结构、进化关系、序列特征及蛋白结构进行剖析。基因结构和蛋白序列特征分析表明:尽管葡萄3个血红蛋白基因外显子个数和保守基序组织结构变异较大,但功能结构域具有高度保守性。结构模拟显示,葡萄VvHb1以单体形式存在,而VvHb2和VvHb3则以二聚体形式存在,尽管它们三维构象以螺旋结构为主,但结合血红素分子活性不同。进化分析揭示,植物血红蛋白具有4个类群,其中葡萄的血红蛋白落入主要类群外,并且单独形成了一个进化分支,说明葡萄血红蛋白基因在物种形成后发生了快速进化和基因扩增现象。 相似文献
9.
After administration of glycine-2-(14)C to a patient with thalassemia, the specific activities of heme and globin of F hemoglobin were consistently higher than those of hemoglobin A. After reaching a maximum, the ratio of the specific activity of heme to that of globin remained constant within each hemoglobin. Explanations considered include dilution by preformed subunits, differential turnover of hemoglobins, and possibly more than one heme-synthesizing pool. 相似文献
10.
Hemoglobin adaptation for fast and slow water habitats in sympatric catostomid fishes 总被引：1，自引：0，他引：1
D A Powers 《Science (New York, N.Y.)》1972,177(46):360-362
The oxygen equilibria of Catostomus insignis hemoglobins are pH dependent. Catostomus clarkii hemoglobins have some components (20 percent) whose oxygen equilibria are independent of pH because the alpha chains have NH(2)-termini that are blocked and the beta chains lack the "usual" COOH-terminal histidine. Since the Bohr effect is normally a beneficial phenomenon, the maintenance of some hemoglobins without a Bohr effect must provide a physiological advantage that is habitat specific. The intrastream ecological preferences of these sympatric catostomids suggest that the hemoglobins without the Bohr effect confer an ecological advantage in a swift water habitat. 相似文献
11.
Hemoglobin interaction: modification of solid phase composition in the sickling phenomenon 总被引：14，自引：0，他引：14
Direct analyses of solid phase formed by deoxygenating solutions of sickle-cell hemoglobin (Hb S) in the presence of certain other hemoglobin species show that hemoglobins A and C can participate in the filamentous fine structure characteristic of the sickling phenomenon. In contrast, fetal hemoglobin (Hb F) is nearly completely excluded. 相似文献
12.
Comparison of the 2.4 angstrom resolution crystal structures of dimeric clam hemoglobin in the deoxygenated and carbon-monoxide liganded states shows how radically different the structural basis for cooperative oxygen binding is from that operative in mammalian hemoglobins. Heme groups are in direct communication across a novel subunit interface formed by the E and F helices. The conformational changes at this interface that accompany ligand binding are more dramatic at a tertiary level but more subtle at a quaternary level than those in mammalian hemoglobins. These findings suggest a cooperative mechanism that links ligation at one subunit with potentiation of affinity at the second subunit. 相似文献
13.
The glycosylation of hemoglobin: relevance to diabetes mellitus 总被引：34，自引：0，他引：34
Glucose reacts nonenzymatically with the NH2-terminal amino acid of the beta chain of human hemoglobin by way of a ketoamine linkage, resulting in the formation of hemoglobin AIc. Other minor components appear to be adducts of glucose 6-phosphate and fructose 1,6-diphosphate. These hemoglobins are formed slowly and continuously throughout the 120-day life-span of the red cell. There is a two- to threefold increase in hemoglobin AIc in the red cells of patients with diabetes mellitus. By providing an integrated measurement of blood glucose, hemoglobin AIc is useful in assessing the degree of diabetic control. Furthermore, this hemoglobin is a useful model of nonenzymatic glycosylation of other proteins that may be involved in the long-term complications of the disease. 相似文献
14.
Protein synthesis: its control in erythropoiesis 总被引：16，自引：0，他引：16
Erythropoiesis in the fetal mouse provides a model to study several important aspects of the regulation of cell differentiation and differentiated protein synthesis. Changes in the patterns of hemoglobins formed during fetal and postfetal development are shown to be associated with the substitution of the liver erythroid cell line. In the course of differentiation of yolk sac erythroid cells there are at least two classes of proteins distinguishable with respect to dependence on continued RNA formatoin. The bulk of nuclear proteins, "nondifferentiated" proteins, appear to be dependent on relatively short-lived messenger RNA while synthesis of differentiated proteins, the hemoglobins, proceeds on relatively stable molecules of messenger RNA. Hemoglobin formation occurs in those cells which are actively synthesizing DNA and dividing. On the average, two to three cell divisions may occur after the formation and stabilization of the messenger RNA for globin. Yolk sac erythropoiesis, at least from day 10 of gestation, is unresponsive to erythropoietin. By comparison, in fetal liver erythropoiesis, the hormone, erythropoietin, acts selectively on the most immature erythroid cell precursor to induce differentiation, cell replication, and hemoglobin formation. The erythropoietin responsive cell in the liver is apparently differentiated from the progenitor, pluripotential stem cell and committed to erythroblast formation and hemoglobin synthesis on exposure to the hormone. The initial effects of erythropoietin on macromolecular synthesis are to stimulate RNA synthesis, which temporally is followed by cell replication and the increase in hemoglobin formation. During liver erythropoiesis, there appears to be a transition from hemoglobin synthesis dependent on RNA formation to hemoglobin synthesis directed by relatively stable messenger RNA. 相似文献
15.
Twenty micromolar hemin causes no change in the rate of division of K562 cells but results in accumulation of 11 to 14 picograms of embryonic and fetal hemoglobins per cell. This effect is reversible, and hemoglobin induction in response to hemin, and loss of hemoglobin upon removal of hemin, can be cyclically repeated. The cells can be indefinitely subcultured in the presence of the inducer. Thus, the control of hemoglobin levels in K562 cells does not depend on irreversible differentiation. 相似文献
16.
Paper electrophoregrams of the hemoglobins from 14 species of fresh- and salt-water fish demonstrated from one to three components. The relative distribution of these fractions was determined for all species. Mobilities of the three hemoglobins of rainbow trout were calculated from moving-boundary patterns. Low anodal mobility at pH 8.8 was characteristic of many species examined. 相似文献
17.
S H Boyer A N Noyes G R Vrablik L J Donaldson E W Schaefer C W Gray T F Thurmon 《Science (New York, N.Y.)》1971,171(967):182-185
Small quantities of unusual hemoglobins were found in 1 of 37 chimpanzees and 2 of 6 gorillas. In each genus these hemoglobins contain unique alpha chains that differ from the ordinary by eight to nine scattered amino acid changes. The unusual chains arise from a hitherto undetected hemoglobin (3)alpha locus. No (3)alpha products are found in most apes; accordingly, (3)alpha is considered synthetically inactive in all but a few reversion mutants. Indirect evidence that the inactive (3)alpha locus is juxtaposed to an active alpha locus together with the supposition that (3)alpha exists in man provides a setting wherein thalassemia might be produced by nonhomologous recombination between two loci. 相似文献
18.
No abnormal hemoglobins were detected in a survey of blood samples from three of the largest aboriginal tribes of Taiwan. Samples from 655 individuals of the Ami, Paiwan, and Atayal tribes were examined by Smithies' method of vertical starch gel electrophoresis at pH 9.0. Only the A hemoglobins were found. 相似文献
19.
Cyrklaff M Sanchez CP Kilian N Bisseye C Simpore J Frischknecht F Lanzer M 《Science (New York, N.Y.)》2011,334(6060):1283-1286
The hemoglobins S and C protect carriers from severe Plasmodium falciparum malaria. Here, we found that these hemoglobinopathies affected the trafficking system that directs parasite-encoded proteins to the surface of infected erythrocytes. Cryoelectron tomography revealed that the parasite generated a host-derived actin cytoskeleton within the cytoplasm of wild-type red blood cells that connected the Maurer's clefts with the host cell membrane and to which transport vesicles were attached. The actin cytoskeleton and the Maurer's clefts were aberrant in erythrocytes containing hemoglobin S or C. Hemoglobin oxidation products, enriched in hemoglobin S and C erythrocytes, inhibited actin polymerization in vitro and may account for the protective role in malaria. 相似文献
20.
Urea is maintained at moderately high concentrations in the blood and tissues of marine elasmobranchs. Functional properties of the hemoglobins fromn several elasmobranch species are unaffected by urea concentrations as high as 5 molar. This in. sensitivity to urea, which is not observed with human hemoglobin, is accompanied by an increased sensitivity to sodium chloride. 相似文献