Hemoglobin Gun Hill: deletion of five amino acid residues and impaired heme-globin binding

Hemoglobin Gun Hill, a new variant of adult hemoglobin, was found in a Caucasian and one of his three daughters. The abnormal hemoglobin had only half of the expected number of heme groups. Five amino acid residues appeared to be missing from the beta-globin chains. These residues occur in linear sequence in normal beta-chains in a region involved in heme-globin binding. A deletion of five amino acids in the beta-chains of hemoglobin Gun Hill is postulated. The most likely mechanism for the origin of such a hemoglobin variant would appear to be unequal crossing-over during meiosis.     

Hemoglobin Hijiyama: a new fast-moving hemoglobin in a Japanese family

A variant of hemoglobin A, named Hb Hijiyama, found in two generations of a Japanese family living in Hiroshima, Japan, has a higher anodal electrophoretic mobility than hemoglobin A; a gain of two negative charges per molecule is indicated. Fingerprinting and amino acid analysis showed the biochemical anomaly to be in the beta chain at residue 120, where lysine is replaced by glutamic acid. In the heterozygote carriers of the abnormal hemoglobin there is no apparent association with clinical or hematologic abnormalities.     

Hemoglobin Portland 1: a new human hemoglobin unique in structure

A new hemoglobin (Hb), Portland 1, has been found in a newborn infant having multiple congenital anomalies and complex autosomal chromosomal mosaicism. The new hemoglobin has a unique tetrameric structure (molecular weight, 66,000) composed of two pairs of different types of chains, neither of which is alpha, gamma(2)x(2). The x-chain of Hb Portland 1 may be a new type of hemoglobin chain, but the available evidence suggests that it may be identical with the epsilon chain. We suggest that Hb Portland 1 is an embryonic hemoglobin that persisted until after birth in relatively large amounts in this patient.     

Hemoglobin Sphakiá: a delta-chain variant of hemoglobin A2 from Crete

A new variant of the normal minor component Hb A(2) has been detected in a family that lives in Sphakiá, Crete. Chemical studies of this abnormal hemoglobin, designated Hb A(2) delta Sphakiá, indicates a substitution of the histidyl residue number two of the delta-chain by an arginyl residue.     

Conversion of a PI-anchored protein to an integral membrane protein by a single amino acid mutation

Qa-2, a cell-surface glycoprotein anchored by phosphatidylinositol (PI), is structurally related to the class I transplantation antigens H-2 K, D, and L, which are integral membrane glycoproteins. The predicted transmembrane segment of Qa-2 differs from those of H-2 K, D, and L by the presence of an aspartate in place of a valine at position 295. A single base change that replaced this aspartate with valine resulted in cell-surface Qa-2 molecules that were insensitive to hydrolysis by a PI-specific phospholipase C and more resistant to papain cleavage, properties shared by H-2D. Cells expressing Asp----Val mutant Qa-2 proteins were still able to attach a PI anchor to endogenous proteins such as Thy-1 and J11D. It therefore appears that this single amino acid change converts Qa-2 from a PI-linked form into an integral membrane protein.     

A single amino acid mutation contributes to adaptive beach mouse color pattern

Natural populations of beach mice exhibit a characteristic color pattern, relative to their mainland conspecifics, driven by natural selection for crypsis. We identified a derived, charge-changing amino acid mutation in the melanocortin-1 receptor (Mc1r) in beach mice, which decreases receptor function. In genetic crosses, allelic variation at Mc1r explains 9.8% to 36.4% of the variation in seven pigmentation traits determining color pattern. The derived Mc1r allele is present in Florida's Gulf Coast beach mice but not in Atlantic coast mice with similar light coloration, suggesting that different molecular mechanisms are responsible for convergent phenotypic evolution. Here, we link a single mutation in the coding region of a pigmentation gene to adaptive quantitative variation in the wild.     

T-cell recognition of Ia molecules selectively altered by a single amino acid substitution

T lymphocytes recognize foreign antigen together with allele-specific determinants on membrane-bound class I and class II (Ia) gene products of the major histocompatibility complex. To identify amino acids of class II molecules critical to this recognition process, the genes encoding the beta chains of the I-Ak molecule were cloned from a wild-type B-cell hybridoma and from an immunoselected variant subline showing distinct serological and T-cell stimulatory properties. Nucleotide sequencing and DNA-mediated gene transfer established that a single base transition (G----A) encoding a change from glutamic acid to lysine at position 67 in the I-Ak beta molecule accounted for all the observed phenotypic changes of the variant cells. These results confirm the importance of residues 62 to 78 in the amino terminal domain of I-A beta for class II-restricted T-cell recognition of antigen and demonstrate the ability of a single substitution in this region to alter this recognition event.     

Membrane anchoring of a human IgG Fc receptor (CD16) determined by a single amino acid

CD16 is a low-affinity immunoglobulin G (IgG) Fc receptor that is expressed on natural killer (NK) cells, granulocytes, activated macrophages, and some T lymphocytes. Two similar genes, CD16-I and CD16-II, encode membrane glycoproteins that are anchored by phosphatidylinositol (PI)-glycan and transmembrane polypeptides, respectively. The primary structural requirements for PI-linkage were examined by constructing a series of hybrid cDNA molecules. Although both cDNA's have an identical COOH-terminal hydrophobic segment, CD16-I has Ser203 whereas CD16-II has Phe203. Conversion of Phe to Ser in CD16-II permits expression of a PI-glycan-anchored glycoprotein, whereas conversion of Ser to Phe in CD16-I prevents PI-glycan linkage.     

猪细小病毒NS1蛋白65-133位氨基酸缺失对其核定位的影响

为了探究猪细小病毒NS1蛋白入核机制,通过生物信息学网站预测PPV NS1核定位序列,根据GenBank上传的PPV非结构蛋白NS1的序列设计NS1扩增引物和一系列重叠PCR引物,以河南省动物性食品安全重点实验室保存的猪细小病毒DNA为模板,扩增NS1和缺失突变体基因,构建真核表达重组质粒pCAGGS-HA-NS1、pCAGGS-HA-NS1_(65-133aaDel)、pCAGGS-HA-NS1_(207-267aaDel)。将其转染至PPV易感猪源细胞系PK-15细胞,通过免疫荧光和Western-blot鉴定NS1和不同的NS1缺失突变体在细胞内的核定位情况。结果表明,pCAGGS-HA-NS1、pCAGGS-HA-NS1_(65-133aaDel)、pCAGGS-HA-NS1_(207-267aaDel)编码蛋白均成功表达。免疫荧光和Western-blot显示NS1和NS1_(207-267aaDel)蛋白定位于细胞核,而NS1_(65-133aaDel)蛋白的细胞定位较NS1发生改变,由细胞核定位改变为细胞质定位,说明PPV NS1蛋白65-133位氨基酸缺失能改变其在细胞内的核定位,PPV NS1蛋白核定位序列NLS存在于NS1的65-133aa处。     

3,4-dihydroxyproline: a new amino acid in diatom cell walls

An analog of proline, 2, 3-cis-3, 4-trans-3, 4-dihydroxy-L-proline, was found in the cell walls of the eight species of diatoms studied and was isolated from the proteinaceous material of the wall of Navicula pelliculosa. The properties of this substance are described; its structure was confirmed by nuclear magnetic resonance spectros-copy.     

Immunoglobulin structure: partial amino acid sequence of a Bence Jones protein

Sequence analysis and ordering of the soluble tryptic peptides of one Bence Jones protein and comparison with partial sequence data for another have revealed many structural differences in the half of the molecule with the terminal amino group, but only one structural difference in the half of the molecule having the terminal carboxyl group. Somatic chromosomal rearrangements may effect such changes and account for variability in antibody structure.     

296位氨基酸位阻效应影响黄花蒿没药醇合酶环化反应的起始

【目的】探究黄花蒿没药醇合酶第296位氨基酸突变抑制环化反应的机制。【方法】利用Quik Change?Multi Site-Directed Mutagenesis的方法将黄花蒿没药醇合酶的296位氨基酸残基由苏氨酸突变成异亮氨酸。原核表达,蛋白纯化后测定其催化特异性。【结果】黄花蒿没药醇合酶T296I体外催化(2E,6E)-法尼基焦磷酸主产物为非环化的法尼烯;但是将T296I蛋白与中间体(3R,6E)-橙花叔醇焦磷酸一起孵育时可生成环化的主产物α-bisabolol,野生型酶的天然产物。【结论】黄花蒿没药醇合酶T296I点突变进一步证明氨基酸残基的空间体积和立体化学是自然环化反应起始的控制关键,其位阻效应能够抑制法尼基焦磷酸向橙花叔醇焦磷酸转化。     

Alteration of alpha 1 Na+,K(+)-ATPase 86Rb+ influx by a single amino acid substitution

The sodium- and potassium-dependent adenosine triphosphatase (Na+,K(+)-ATPase) maintains the transmembrane Na+ gradient to which is coupled all active cellular transport systems. The R and S alleles of the gene encoding the Na+,K(+)-ATPase alpha 1 subunit isoform were identified in Dahl salt-resistant (DR) and Dahl salt-sensitive (DS) rats, respectively. Characterization of the S allele-specific Na+,K(+)-ATPase alpha 1 complementary DNA identified a leucine substitution of glutamine at position 276. This mutation alters the hydropathy profile of a region in proximity to T3(Na), the trypsin-sensitive site that is only detected in the presence of Na+. This mutation causes a decrease in the rubidium-86 influx of S allele-specific sodium pumps, thus marking a domain in the Na+,K(+)-ATPase alpha subunit important for K+ transport, and supporting the hypothesis of a putative role of these pumps in hypertension.     

Deciphering the message in protein sequences: tolerance to amino acid substitutions

An amino acid sequence encodes a message that determines the shape and function of a protein. This message is highly degenerate in that many different sequences can code for proteins with essentially the same structure and activity. Comparison of different sequences with similar messages can reveal key features of the code and improve understanding of how a protein folds and how it performs its function.     

Ribonucleic acid metabolism of a single neuron: correlation with electrical activity

The giant neuron of the abdominal ganglion of Aplysia californica incorporates tritiated uridine into RNA at a constant rate at rest. This rate incrceases under synaptic stimulation, the increase being directly proportional to the number of action potentials produced by the neuron. Multineuronal samples from stimulated ganglia faiiled to show an increase in incorporation.     

Rabbit hemoglobin biosynthesis: use of human hemoglobin chains to study molecule completion

A cell-free protein-synthesizing system made from rabbit reticulocytes was used to incorporate (14)C-amino acids into hemoglobin. Electrophoretic analyses of the soluble products of this cell-free system revealed a fraction containing rabbit (14)C-alpha chains in addition to the rabbit (14)C-hemoglobin. The addition of isolated human hemoglobin beta chains to this system during active synthesis inhibited the release of newly synthesized rabbit (14)C-beta chains into solution from the ribosome fraction. This inhibition was possibly a result of hybrid hemoglobin formation between rabbit alpha and human beta chains. A model of hemoglobin construction in which soluble alpha chains are intermediates is suggested. These alpha chains may aid in the release of beta chains from the polyribosomes during the completion of the hemoglobin molecule.     

大田作物秸秆量评估中秸秆系数取值研究

本研究对《中国统计年鉴》各省的大田作物的不同种类,根据2006—2011年报导的秸秆系数的实测值,研究确定各省市自治区(除港、澳、台外)各类大田作物的秸秆系数取值,以数学模拟取值法对水稻、小麦和玉米3大作物进行取值,以相同或相似地区平均取值法、同类作物取值法确定其他作物取值。结果表明:水稻的秸秆系数取值变幅为0.74～1.33,全国平均值为1.04。小麦的变幅为1.05～1.41,全国平均值为1.28。玉米的变幅为0.93～1.30,全国平均值为1.07。豆类和薯类的变幅分别为1.13～1.86和0.42～0.75,全国平均值分别为1.35和0.53。黄红麻和棉花的秸秆系数的变幅分别为1.22～2.23和2.41～4.09,全国平均值分别为1.73和2.87。花生、油菜和芝麻的变幅分别为0.85～1.43、2.57～3.17和1.78～2.23,全国平均值分别为0.99、2.90和1.89。甘蔗的秸秆系数在各省统一取值为0.34。甜菜和烟草的变幅分别为0.18～0.67和0.49～0.92,全国平均值分别为0.37和0.66。"其他谷类"、"其他油料"和"其他麻类"的秸秆系数在各省取值均相同,分别为2.32、2.63和6.55。     

Synthesis of a sulfur-containing amino acid under simulated prebiotic conditions

Ultraviolet irradiation of an aqueous solution of ammonium thiocyanate produces the sulfur-containing amino acid methionine. Synthesis of this class of biocompound fills another important gap in development of an overall picture of how prebiological chemistry may have evolved on primitive Earth.