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排序方式: 共有734条查询结果,搜索用时 390 毫秒
1.
Coronary artery bypass grafts: visualization with MR imaging 总被引:1,自引:0,他引:1
2.
The neurotransmitter biosynthetic enzymes, tyrosine hydroxylase (TH), and tryptophan hydroxylase (TPH) are each composed of
an amino-terminal regulatory domain and a carboxylterminal catalytic domain. A chimeric hydroxylase was generated by coupling
the regulatory domain of TH (TH-R) to the catalytic domain of TPH (TPH-C) and expressing the recombinant enzyme in bacteria.
The chimeric junction was created at proline 165 in TH and proline 106 in TPH because this residue is within a conserved five
amino-acid span (ValProTrpPhePro) that defines the beginning of the highly homologous catalytic domains of TH and TPH. Radioenzymatic
activity assays demonstrated that the TH-R/TPH-C chimera hydroxylates tryptophan, but not tyrosine. Therefore, the regulatory
domain does not confer substrate specificity. Although the TH-R/TPH-C enzyme did serve as a substrate for protein kinase (PKA),
activation was not observed following phosphorylation. Phosphorylation studies in combination with kinetic data provided evidence
that TH-R does not exert a dominant influence on TPH-C. Stability assays revealed that, whereas TH exhibited a t1/2 of 84 min at 37°C, TPH was much less stable (t
1/2=28.3 min). The stability profile of TH-R/TPH-C, however, was superimposable on that of TH. Removal of the regulatory domain
(a deletion of 165 amino acids from the N-terminus) of TH rendered the catalytic domain highly unstable, as demonstrated by
at
1/2 of 14 min. The authors conclude that the regulatory domain of TH functions as a stabilizer of enzyme activity. As a corollary,
the well-characterized instability of TPH may be attributed to the inability of its regulatory domain to stabilize the catalytic
domain. 相似文献
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6.
Genotype-phenotype correlation for nucleotide substitutions in the IgII- IgIII linker of FGFR2 总被引:6,自引:3,他引:3
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9.
Localization of a gene for otosclerosis to chromosome 15q25-q26 总被引:5,自引:0,他引:5
Tomek MS; Brown MR; Mani SR; Ramesh A; Srisailapathy CR; Coucke P; Zbar RI; Bell AM; McGuirt WT; Fukushima K; Willems PJ; Van Camp G; Smith RJ 《Human molecular genetics》1998,7(2):285-290
Among white adults otosclerosis is the single most common cause of hearing
impairment. Although the genetics of this disease are controversial, the
majority of studies indicate autosomal dominant inheritance with reduced
penetrance. We studied a large multi- generational family in which
otosclerosis has been inherited in an autosomal dominant pattern. Five of16
affected persons have surgically confirmed otosclerosis; the remaining nine
have a conductive hearing loss but have not undergone corrective surgery.
To locate the disease- causing gene we completed genetic linkage analysis
using short tandem repeat polymorphisms (STRPs) distributed over the entire
genome. Multipoint linkage analysis showed that only one genomic region, on
chromosome 15q, generated a lod score >2.0. Additional STRPs were typed
in this area, resulting in a lod score of 3.4. STRPs FES (centromeric) and
D15S657 (telomeric) flank the 14. 5 cM region that contains an otosclerosis
gene.
相似文献
10.
Summary The authors report the results of 115 dissections of the base of the distal phalanx of fingers and toes. In 85% of cases including hypoplastic supernumerary digits, there is a connective ligament-like structure. It is a dorsal expansion of the lateral ligament of the distal inter-phalangeal joint arising from the intermediate phalanx and ending in the matrix and the lunula. This ligament may have a role in biomechanical strains on the nail. It can explain some dystrophic nails associated with some malpositioned joints in fingers or toes.
Structure ligamentaire de la base de l'ongle
Résumé Les auteurs rapportent les résultats de 115 dissections portant sur la base de la phalange distale des doigts ou des orteils. Ils retrouvent dans 85 % des cas, y compris sur des doigts hypoplasiques surnuméraires, une formation conjonctive de type ligamentaire. Il s'agit d'une expansion dorsale du ligament latéral de l'articulation interphalangienne distale, naissant de l'extrémité distale de la phalange intermédiaire et se terminant au sein de la matrice et sur la lunule. Ce ligament ostéomatriciel peut jouer un rôle dans la transmission des contraintes biomécaniques sur l'ongle et expliquer les dystrophies unguéales stéréotypées associées à certaines malpositions articulaires des doigts ou des orteils.相似文献