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101.
R. J. Siezen J. A. Leunissen 《Protein science : a publication of the Protein Society》1997,6(3):501-523
Subtilases are members of the clan (or superfamily) of subtilisin-like serine proteases. Over 200 subtilases are presently known, more than 170 of which with their complete amino acid sequence. In this update of our previous overview (Siezen RJ, de Vos WM, Leunissen JAM, Dijkstra BW, 1991, Protein Eng 4:719-731), details of more than 100 new subtilases discovered in the past five years are summarized, and amino acid sequences of their catalytic domains are compared in a multiple sequence alignment. Based on sequence homology, a subdivision into six families is proposed. Highly conserved residues of the catalytic domain are identified, as are large or unusual deletions and insertions. Predictions have been updated for Ca(2+)-binding sites, disulfide bonds, and substrate specificity, based on both sequence alignment and three-dimensional homology modeling. 相似文献
102.
Characterization of a Small Family (CAIII) of Microsatellite-Containing Sequences with X-Y Homology 总被引:4,自引:0,他引:4
Patrizia Malaspina Bianca Maria Ciminelli Luigi Viggiano Carla Jodice Fulvio Cruciani Piero Santolamazza Daniele Sellitto Rosaria Scozzari Luciano Terrenato Mariano Rocchi Andrea Novelletto 《Journal of molecular evolution》1997,44(6):652-659
Four X-linked loci showing homology with a previously described Y-linked polymorphic locus (DYS413) were identified and characterized.
By fluorescent in situ hybridization (FISH), somatic cell hybrids, and YAC screening, the X-linked members of this small family
of sequences (CAIII) all map in Xp22, while the Y members map in Yq11. These loci contribute to the overall similarity of
the two genomic regions. All of the CAIII loci contain an internal microsatellite of the (CA)n type. The microsatellites display extensive length polymorphism in two of the X-linked members as well as in the Y members.
In addition, common sequence variants are found in the portions flanking the microsatellites in two of the X-linked members.
Our results indicate that, during the evolution of this family, length variation on the Y chromosome was accumulated at a
rate not slower than that on the X chromosome. Finally, these sequences represent a model system with which to analyze human
populations for similar X- and Y-linked polymorphisms.
Received: 29 July 1996 / Accepted: 15 January 1997 相似文献
103.
M J DE. MAINE 《The Annals of applied biology》1995,127(1):151-156
Dihaploids obtained from a somatically chromosome-doubled dihaploid potato were crossed with Solanum phureja clones. To test the effect of inbreeding, measurements were made of their seed production and the tuber yield, tuber number and mean tuber weight of their offspring. On average, seed production of the second generation dihaploids was higher than that of the original dihaploid progenitor. Progeny tuber yield and its components were little different from those of the original dihaploid's progeny. Tuber flesh quality, as measured lack of blemishes, was better in the offspring of second generation dihaploids.
It is suggested that the negative effects of producing second generation dihaploids are minor compared with producing the first generation dihaploid from a tetraploid, because most deleterious recessives have already been unmasked. The results indicated residual variation within the original dihaploid which could be exploited for plant breeding purposes.
An indicator of inbred status, alternative to the inbreeding coefficient, is suggested which could be applied to both diploids and tetraploids. 相似文献
It is suggested that the negative effects of producing second generation dihaploids are minor compared with producing the first generation dihaploid from a tetraploid, because most deleterious recessives have already been unmasked. The results indicated residual variation within the original dihaploid which could be exploited for plant breeding purposes.
An indicator of inbred status, alternative to the inbreeding coefficient, is suggested which could be applied to both diploids and tetraploids. 相似文献
104.
Intergeneric hybridizations were made betweenT. elongatum, and twoPsathyrostachys and fiveLeymus species. The seed set obtained onT. elongatum ×Leymus hybrids ranged from 5.65% to 20.00%, depending onLeymus species. The seed set obtained onT. elongatum ×Psathyrostachys hybrids ranged from 16.07% to 19.70%. Meiotic pairing at metaphase-I in JN diploid hybrids ofT. elongatum ×Psathyrostachys species revealed a very low level homology between the basic J and N genomes, and further demonstrated that the two genomes are quite diverged. Chromosome pairing in theT. elongatum ×Leymus secalinus hybrid averaged 15.19 univalents + 2.62 rod bivalents + 0.26 ring bivalents + 0.02 trivalents, suggesting that the partial Je chromosomes ofT. elongatum has homology withLeymus secalinus genomes.L. secalinus might have 3–4 chromosomes originating from Je genome. 相似文献
105.
A secondary structure has been predicted for the protein kinase C2 regulatory domain found in homologous form in synaptotagmin, some phospholipases, and some GTP activated proteins. The proposed structure is built from seven consecutive beta strands followed by a terminal alpha helix. Considerations of overall surface exposure of individual secondary structural elements suggest that these are packed into a 2-sheet beta sandwich structure, with one of only three of the many possible folds being preferred. © 1995 Wiley-Liss, Inc. 相似文献
106.
A simple and fast approach to prediction of protein secondary structure from multiply aligned sequences with accuracy above 70%. 总被引:3,自引:3,他引:0
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P. K. Mehta J. Heringa P. Argos 《Protein science : a publication of the Protein Society》1995,4(12):2517-2525
To improve secondary structure predictions in protein sequences, the information residing in multiple sequence alignments of substituted but structurally related proteins is exploited. A database comprised of 70 protein families and a total of 2,500 sequences, some of which were aligned by tertiary structural superpositions, was used to calculate residue exchange weight matrices within alpha-helical, beta-strand, and coil substructures, respectively. Secondary structure predictions were made based on the observed residue substitutions in local regions of the multiple alignments and the largest possible associated exchange weights in each of the three matrix types. Comparison of the observed and predicted secondary structure on a per-residue basis yielded a mean accuracy of 72.2%. Individual alpha-helix, beta-strand, and coil states were respectively predicted at 66.7, and 75.8% correctness, representing a well-balanced three-state prediction. The accuracy level, verified by cross-validation through jack-knife tests on all protein families, dropped, on average, to only 70.9%, indicating the rigor of the prediction procedure. On the basis of robustness, conceptual clarity, accuracy, and executable efficiency, the method has considerable advantage, especially with its sole reliance on amino acid substitutions within structurally related proteins. 相似文献
107.
蓟属两种植物的染色体研究 总被引:2,自引:0,他引:2
本文对蓟属(Cirsium)的两个形态相似的近缘种大刺儿菜和小刺儿菜进行了染色体研究,其中后者为首次报道。观察结果表明:两个种的染色体数目均为2n=2x=34:它们的核型是:大刺儿菜.2n=2x=34=20m+12sm+2st:小刺儿菜.2n=2x=34=22m+10km(2SAT)+2st。通过核型比较,认为它们是两个独立的种.而且后者比前者进化。 相似文献
108.
继前面的工作把测试蛋白从三族扩大到十一族,寻求联配参数的普适“缺省值“;比较不同的主链曲率和挠率的计算方法,进一步确认主链的折红红分几何刻划方法的有效性;寻找有效的可变缺失突变惩罚函数的形式。结果表明,编制的蛋白质多重联配软件系统是满意的,可用于蛋白质三维结构预测。 相似文献
109.
Conservation of interphase chromatin nonhistone antigens as components of metaphase chromosomes 总被引:1,自引:0,他引:1
K W Adolph 《FEBS letters》1984,165(2):211-215
The degree of conservation of HeLa interphase chromatin nonhistone antigens among the nonhistones of isolated metaphase chromosomes was determined with immunological procedures. Proteins were separated on SDS-polyacrylamide gels and electrophoretically transferred to diazophenylthioether (DPT)-paper, which was then overlaid with antiserum to chromatin from interphase nuclei. The bound antibodies were detected with 125I-labeled protein A. Alternatively, polyacrylamide gels were directly overlaid with antiserum and with 125I-protein A. Densitometry of autoradiograms and stained gels revealed the degree of conservation of nonhistone antigenic determinants from interphase to metaphase to be over 90% for chromatin. 相似文献
110.
Assessment of a model for intron RNA secondary structure relevant to RNA self-splicing--a review 总被引:36,自引:0,他引:36
A widespread class of introns is characterized by a particular RNA secondary structure, based upon four conserved nucleotide sequences. Among such "class I" introns are found the majority of introns in fungal mitochondrial genes and the self-splicing intron of the large ribosomal RNA of several species of Tetrahymena. A model of the RNA secondary structure, which must underlie the self-splicing activity, is here evaluated in the light of data on 16 further introns. The main body or "core structure" of the intron always consists of the base-paired regions P3 to P9 with the associated single-stranded loops, with P2 present also in most cases. Two minority sub-classes of core structure occur, one of which is typical of introns in fungal ribosomal RNA. Introns in which the core structure is close to the 5' splice site all have an internal guide sequence (IGS) which can pair with exon sequences adjacent to the 5' and 3' splice sites to align them precisely, as proposed by Davies et al. [Nature 300 (1982) 719-724]. In these cases, the internal guide model allows us to predict correctly the exact location of splice sites. All other introns probably use other mechanisms of alignment. This analysis provides strong support for the RNA splicing model which we have developed. 相似文献