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71.
Isolation and characterization of a mutation that alters the substrate specificity of the Escherichia coli glucose permease. 下载免费PDF全文
G S Begley K A Warner J C Arents P W Postma G R Jacobson 《Journal of bacteriology》1996,178(3):940-942
We isolated 10 mannitol-positive mutants from a mannitol-negative Escherichia coli strain. These mutations mapped within ptsG, encoding the glucose permease (EIIGlc), and resulted in a G-320-to-V substitution that allows EIIGlc to transport mannitol. Gly-320 lies within a putative transmembrane helix of EIIGlc that may be involved in substrate recognition. 相似文献
72.
M. D. Weston P. M. Kelley L. D. Overbeck M. Wagenaar D. J. Orten T. Hasson Z. Y. Chen D. Corey M. Mooseker J. Sumegi C. Cremers C. Moller S. G. Jacobson M. B. Gorin W. J. Kimberling 《American journal of human genetics》1996,59(5):1074-1083
Usher syndrome type 1b (USH1B) is an autosomal recessive disorder characterized by congenital profound hearing loss, vestibular abnormalities, and retinitis pigmentosa. The disorder has recently been shown to be caused by mutations in the myosin VIIa gene (MYO7A) located on 11q14. In the current study, a panel of 189 genetically independent Usher I cases were screened for the presence of mutations in the N-terminal coding portion of the motor domain of MYO7A by heteroduplex analysis of 14 exons. Twenty-three mutations were found segregating with the disease in 20 families. Of the 23 mutations, 13 were unique, and 2 of the 13 unique mutations (Arg212His and Arg212Cys) accounted for the greatest percentage of observed mutant alleles (8/23, 31%). Six of the 13 mutations caused premature stop codons, 6 caused changes in the amino acid sequence of the myosin VIIa protein, and 1 resulted in a splicing defect. Three patients were homozygotes or compound heterozygotes for mutant alleles; these three cases were Tyr333Stop/Tyr333Stop, Arg212His-Arg302His/Arg212His-Arg302His, and IVS13nt-8c-->g/Glu450Gln. All the other USH1B mutations observed were simple heterozygotes, and it is presumed that the mutation on the other allele is present in the unscreened regions of the gene. None of the mutations reported here were observed in 96 unrelated control samples, although several polymorphisms were detected. These results add three patients to single case reported previously where mutations have been found in both alleles and raises the total number of unique mutations in MYO7A to 16. 相似文献
73.
Hyuntae Kim Elaine L. Jacobson Myron K. Jacobson 《Molecular and cellular biochemistry》1994,138(1-2):237-243
NAD glycohydrolases are the longest known enzymes that catalyze ADP-ribose transfer. The function of these ubiquitous, membrane-bound enzymes has been a long standing puzzle. The NAD glycohydrolase are briefly reviewed in light of the discovery by our laboratory that NAD glycohydrolases are bifunctional enzymes that can catalyze both the synthesis and hydrolysis of cyclic ADP-ribose, a putative second messenger of calcium homeostasis.Abbreviations NADase
nicotinamide adenine dinucleotide glycohydrolase
- NAD
nicotinamide adenine dinucleotide
- ADP-ribose
adenosine diphosphoribose
- cADPR
cyclic adenosine diphosphoribose 相似文献
74.
J A Jacobson B E White M P Battin L P Francis D J Green E S Kasworm 《The Western journal of medicine》1994,161(3):232-236
The Patient Self-Determination Act was implemented in December 1991. Before and after its implementation, we used a structured interview of 302 randomly selected patients to determine their awareness, understanding, and use of advance directives. Implementation of the Act did not have a major effect on these. Although more than 90% of patients were aware of the living will, only about a third selected the correct definition or the correct circumstances in which it applied, and less than 20% of patients had completed one. About a third of patients were aware of a Durable Power of Attorney for Health Care and chose the correct definition, and about half identified the correct circumstances in which it applies; less than 10% had completed such a document. Surprisingly, patients who said they had completed advance directives did not demonstrate better understanding of these documents. Our results indicate that many patients, including some who have completed advance directives, do not fully understand them. It may be unwise to regard these documents as carefully considered, compelling statements of patients'' preferences. Appropriate responses to our findings include increased public education, revising state statutes to bring them into congruence with public perception, and expanding the dialogue between physicians and patients. 相似文献
75.
Gary R. Jacobson Cynthia Saraceni-Richards 《Journal of bioenergetics and biomembranes》1993,25(6):621-626
The bacterial phosphoenolpyruvate-dependent carbohydrate phosphotransferase system (PTS) consists of several proteins whose primary functions are to transport and phosphorylate their substrates. The complexity of the PTS undoubtedly reflects its additional roles in chemotaxis to PTS substrates and in regulation of other metabolic processes in the cell. The PTS permeases (Enzymes II) are the membrane-associated proteins of the PTS that sequentially recognize, transport, and phosphorylate their specific substrates in separate steps, and theEscherichia coli mannitol permease is one of the best studied of these proteins. It consists of two cytoplasmic domains (EIIA and EIIB) involved in mannitol phosphorylation and an integral membrane domain (EIIC) which is sufficient to bind mannitol, but which transports mannitol at a rate that is dependent on phosphorylation of the EIIA and EIIB domains. Recent results show that several residues in a hydrophilic, 85-residue segment of the EIIC domain are important for the binding, transport, and phosphorylation of mannitol. This segment may be at least partially exposed to the cytoplasm of the cell. A model is proposed in which this region of the EIIC domain is crucial in coupling phosphorylation of the EIIB domain to transport through the EIIC domain of the mannitol permease. 相似文献
76.
Shaun O. SommererJohn David BakerWilliam P. Jensen Abdul HamzaRobert A. Jacobson 《Inorganica chimica acta》1993,210(2)
An X-ray structural analysis of bis-2,2′,N,N′-bipyridyl ketone cobalt(III) nitrate dihydrate, CoC22H20N4O4+· NO3−·2H2O,Mr=559.38 g/mol, P
, a=8.862(2), b=16.195(3), c=8.772(2) Å, α=103.54(2), β=95.74(3), γ=105.07°, V=1164.4(4) Å3, Z=2, Dx=1.595 g/cm3, Mo Kα radiation (λ=0.71073 Å), μ=7.8 cm−1 and R=0.079, revealed a Co(III) cation in a slightly distorted octahedral environment. The structure reveals that the ligand di-2-pyridyl ketone (dpk) has undergone a hydration reaction across the ketone double bond and one of the hydrate oxygen atoms coordinated to the metal forming a tridentate chelate. This new Co(dpk-hydrate)2+ complex displays the least distorted geometry yet reported for either 1:1 or 1:2 (metal:ligand) complexes. A geometry optimization using the INDO model Hamiltonian as implemented in the program ZINDO was performed on the title complex with the Co3+ modeled as a singlet. The result of the computation corroborates the geometry of the title complex as that expected for Co3+. 相似文献
77.
Biochemical and genetic evidence for a pseudoknot structure at the 3' terminus of the poliovirus RNA genome and its role in viral RNA amplification. 总被引:28,自引:23,他引:5 下载免费PDF全文
The sequences in the plus-stranded poliovirus RNA genome that dictate the specific amplification of viral RNA in infected cells remain unknown. We have analyzed the structure of the 3' noncoding region of the viral genome by thermodynamic-based structure calculation and by chemical and enzymatic probing of in vitro-synthesized RNAs and provide evidence for the existence of an RNA pseudoknot structure in this region. To explore the functional significance of this structure, revertants of a mutant bearing a lesion in the proposed pseudoknot and exhibiting a temperature-sensitive defect in viral RNA synthesis were isolated and mapped. The results of this genetic analysis established a correlation between the structure of the 3' terminus of the viral RNA and its function in vivo in RNA amplification. Furthermore, phylogenetic analysis indicated that a similar structure could be formed in coxsackievirus B1, a related enterovirus, which further supports a role for the pseudoknot structure in viral RNA amplification in infected cells. 相似文献
78.
79.
David Jacobson 《Medical anthropology quarterly》2003,17(1):126-127
Studying Those Who Study Us: An Anthropologist in the World of Artificial Intelligence. Diana E. Forsythe. Edited, with introduction by David Hess. Stanford: Stanford University Press, 2001. xxix. 240 pp. 相似文献
80.