Abstract:
:Negative cooperativity has been observed in CTP synthetase, an allosteric enzyme which contains a regulatory site. Thus, the same enzyme exhibits negative cooperativity for GTP (an effector) and glutamine (a substrate) and positive cooperativity for ATP and UTP (both substrates). In the process of the delineation of these phenomena, diagnostic procedures for negative cooperativity were developed. Application of these procedures to other enzymes indicates that negative cooperativity is a characteristic of many of them. These findings add strong support for the sequential model of subunit interactions which postulates that ligand-induced conformational changes are responsible for regulatory and cooperative phenomena in enzymes.
journal_name
Proc Natl Acad Sci U S Aauthors
Levitzki A,Koshland DE Jrdoi
10.1073/pnas.62.4.1121subject
Has Abstractpub_date
1969-04-01 00:00:00pages
1121-8issue
4eissn
0027-8424issn
1091-6490journal_volume
62pub_type
杂志文章abstract::By employing the nuclear DNA of the African rice Oryza glaberrima as a reference genome, the timing, natures, mechanisms, and specificities of recent sequence evolution in the indica and japonica subspecies of Oryza sativa were identified. The data indicate that the genome sizes of both indica and japonica have increa...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0403715101
更新日期:2004-08-24 00:00:00
abstract::Metabolic engineering seeks to reprogram microbial cells to efficiently and sustainably produce value-added compounds. Since chemical production can be at odds with the cell's natural objectives, strategies have been developed to balance conflicting goals. For example, dynamic regulation modulates gene expression to f...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1911144116
更新日期:2019-12-17 00:00:00
abstract::Previous studies have identified nuclear matrix attachment regions (MARs) that are closely associated with transcriptional enhancers in the IgH, Igkappa, and T cell receptor (TCR) beta loci, but have yielded conflicting information regarding their functional significance. In this report, a combination of in vitro and ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.96.21.11970
更新日期:1999-10-12 00:00:00
abstract::We previously found that a minor fraction of single-stranded DNA (ss-DNA) isolated from native nuclear DNA of normal chicken embryonic cells and cells of other species hybridized with bulk nuclear DNA or cellular RNA in great excess. At least one-third of ss-DNA belonging to the nonrepetitious part of the cell genome ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.74.9.3720
更新日期:1977-09-01 00:00:00
abstract::Humans routinely formulate plans in domains so complex that even the most powerful computers are taxed. To do so, they seem to avail themselves of many strategies and heuristics that efficiently simplify, approximate, and hierarchically decompose hard tasks into simpler subtasks. Theoretical and cognitive research has...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1414219112
更新日期:2015-03-10 00:00:00
abstract::The mammalian retina contains an autonomous circadian clock system that controls many physiological functions within this tissue. Previous studies on young mice have reported that removal of the key circadian clock gene Bmal1 from the retina affects the circadian regulation of visual function, but does not affect phot...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1808137115
更新日期:2018-12-18 00:00:00
abstract::Several overlapping chromosomal deletions spanning the albino locus in the mouse cause perinatal lethality when homozygous and a block in the transcriptional induction of various unlinked hepatocyte-specific genes. Studies of such lethal albino deletion homozygotes in perinatal stages revealed a deficiency in the tran...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.89.14.6540
更新日期:1992-07-15 00:00:00
abstract::Skeletal muscle fibers are defined by patterned covariation of key traits that determine contractile and metabolic characteristics. Although the functional properties of most skeletal muscles result from their proportional content of a few conserved muscle fiber types, some, typically craniofacial, muscles exhibit fib...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.211257298
更新日期:2001-10-09 00:00:00
abstract::Harvey and Kirsten murine sarcoma viruses each encode a structurally and functionally related 21-kilodalton protein (p21), which is the transforming protein of each virus. Using probes from the 0.9-kilobase (kb) p21-coding region of each virus (called v-Ha-ras and v-Ki-ras, respectively), we have molecularly cloned fr...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.79.16.4848
更新日期:1982-08-01 00:00:00
abstract::We have used a motif-based structural search method to identify structural homologs of the hormone binding domains of the nuclear receptors from among a set of known protein structures and have found the closest similarity with members of the subtilisin-like serine proteases. These proteins consist of an open twisted ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.90.21.9949
更新日期:1993-11-01 00:00:00
abstract::Human skin and lung mast cells and rodent peritoneal mast cells contain a carboxypeptidase in their secretory granules. We have screened human lung cDNA libraries with a mouse mast cell carboxypeptidase A (MC-CPA) cDNA probe to isolate a near-full-length cDNA that encodes human MC-CPA. The 5' end of the human MC-CPA t...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.86.23.9480
更新日期:1989-12-01 00:00:00
abstract::The Parkinson's disease (PD) substantia nigra is characterized by the presence of Lewy bodies containing fibrillar alpha-synuclein. Early-onset PD has been linked to two point mutations in the gene that encodes alpha-synuclein, suggesting that disease may arise from accelerated fibrillization. However, the identity of...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.97.2.571
更新日期:2000-01-18 00:00:00
abstract::Earlier papers demonstrated an extensive genetic exchange among fluorescent Pseudomonads; this one documents for genes specifying enzymes of peripheral dissimilation an extrachromosomal array, segregation, and frequent interstrain transfer. An hypothesis is presented of a general mechanism for the formation and mainte...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.70.3.885
更新日期:1973-03-01 00:00:00
abstract::Selection of aptamers from nucleic acid libraries by in vitro evolution represents a powerful method of identifying high-affinity ligands for a broad range of molecular targets. Nevertheless, a sizeable fraction of proteins remain difficult targets due to inherently limited chemical diversity of nucleic acids. We have...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1213933109
更新日期:2012-12-04 00:00:00
abstract::Oxidative stress exacerbates neovascularization (NV) in many disease processes. In this study we investigated the mechanism of that effect. Mice deficient in superoxide dismutase 1 (Sod1(-/-) mice) have increased oxidative stress and show severe ocular NV that is reduced to baseline by antioxidants. Compared with wild...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1012859108
更新日期:2011-08-30 00:00:00
abstract::We report the crystal structure of a translation termination complex formed by the Thermus thermophilus 70S ribosome bound with release factor RF2, in response to a UAA stop codon, solved at 3 A resolution. The backbone of helix alpha5 and the side chain of serine of the conserved SPF motif of RF2 recognize U1 and A2 ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0810953105
更新日期:2008-12-16 00:00:00
abstract::Light chains were obtained from IgG rabbit antibodies to the group-specific carbohydrates of groups A and C streptococci. An analysis of the amino acid alternatives which exist at the first three positions of the N-terminus in both light-chain preparations shows a marked restriction in amino acid sequence heterogeneit...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.63.3.890
更新日期:1969-07-01 00:00:00
abstract::Nuclear import of classical nuclear localization sequence-bearing proteins is mediated by karyopherin alpha/beta1 heterodimers. A second nuclear import pathway, mediated by karyopherin beta2 (transportin), recently was described for mRNA-binding proteins. Here we report the cloning and characterization of human karyop...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.94.9.4451
更新日期:1997-04-29 00:00:00
abstract::The ability to grow the marine molluse Aplysia under laboratory conditions allows a detailed study of the formation of the nervous system and of the development of specific identified cells. I have found that the ganglia develop in a specific temporal order. Cerebral and pedal ganglia develop at hatching, the abdomina...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.74.1.375
更新日期:1977-01-01 00:00:00
abstract::Integrin alphanubeta3 is found on a subset of tumor blood vessels where it is associated with angiogenesis and malignant tumor growth. We designed an alphanubeta3-targeted nanoparticle (NP) encapsulating the cytotoxic drug doxorubicin (Dox) for targeted drug delivery to the alphanubeta3-expressing tumor vasculature. W...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0803728105
更新日期:2008-07-08 00:00:00
abstract::In a subclone derived from mouse L(tk-) cells, we found a plasmid present in a high copy number (greater than 5000 copies per cell) that was stably maintained extrachromosomally without any cytopathic effect to the host cells. This plasmid, termed L factor, has two forms: 5.3 and 5.5 kilobase pairs. DNA sequencing and...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.84.7.1789
更新日期:1987-04-01 00:00:00
abstract::Microbial pathogens with the ability to establish chronic infections have evolved strategies to actively modulate the host immune response. Brucellosis is a disease caused by a Gram-negative intracellular pathogen that if not treated during the initial phase of the infection becomes chronic as the bacteria persist for...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0603362103
更新日期:2006-10-31 00:00:00
abstract::Siglecs are a recently discovered family of animal lectins that belong to the Ig superfamily and recognize sialic acids (Sias). CD33-related Siglecs (CD33rSiglecs) are a subgroup with as-yet-unknown functions, characterized by sequence homology, expression on innate immune cells, conserved cytosolic tyrosine-based sig...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0404833101
更新日期:2004-09-07 00:00:00
abstract::Dopamine is believed to contribute to the degeneration of dopamine-containing neurons in the brain. However, whether dopamine affects the survival of other neuronal populations has remained unclear. Here we document that mice with persistently elevated extracellular dopamine, resulting from inactivation of the dopamin...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1831768100
更新日期:2003-09-16 00:00:00
abstract::As an electron transfer-driven proton pump, cytochrome c oxidase (ferrocytochrome-c:oxygen oxidoreductase, EC 1.9.3.1) must alternate between two conformations in each valence state of the redox element associated with ion translocation. Using second derivative absorption spectroscopy, the conformation of the cytochro...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.88.16.7281
更新日期:1991-08-15 00:00:00
abstract::Candidate single-nucleotide polymorphisms (SNPs) were analyzed for associations to an unselected whole genome pool of tumor mRNA transcripts in 50 unrelated patients with breast cancer. SNPs were selected from 203 candidate genes of the reactive oxygen species pathway. We describe a general statistical framework for t...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0601893103
更新日期:2006-05-16 00:00:00
abstract::Heat shock factors (HSFs) are the master regulators of transcription under protein-damaging conditions, acting in an environment where the overall transcription is silenced. We determined the genomewide transcriptional program that is rapidly provoked by HSF1 and HSF2 under acute stress in human cells. Our results rev...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1305275110
更新日期:2013-09-03 00:00:00
abstract::Diversity in 39 HLA-A, -B, and -C molecules is derived from 20 amino acid positions of high variability and 71 positions of low variability. Variation in the structurally homologous alpha 1 and alpha 2 domains is distinct and may correlate with partial segregation of peptide and T-cell receptor binding functions. Comp...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.85.11.4005
更新日期:1988-06-01 00:00:00
abstract::The Drake Passage (DP) is the major geographic constriction for the Antarctic Circumpolar Current (ACC) and exerts a strong control on the exchange of physical, chemical, and biological properties between the Atlantic, Pacific, and Indian Ocean basins. Resolving changes in the flow of circumpolar water masses through ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.1509203112
更新日期:2015-11-03 00:00:00
abstract::Assemblies formed by solid particles at interfaces have been widely studied because they serve as models of molecular phenomena, including molecular self-assembly. Solid particles adsorbed at interfaces also provide a means of stabilizing liquid-liquid emulsions and synthesizing materials with tunable mechanical, opti...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.0910931107
更新日期:2010-03-02 00:00:00