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1.
Summary Deficiency of dietary carotenoid and vitamin A caused an absence of photoperiodic response of diapause induction in the silkworm,Bombyx mori, and an addition of vitamin A to the diet restored the response. By high pressure liquid chromatography (HPLC) a possible photoperiodic receptor of the silkworm brain was found to contain both retinal and 3-hydroxyretinal which are chromophores of insect visual pigments. These pieces of evidence suggest that a retinoid protein might function in the photoperiodic response of the silkworm. 相似文献
2.
Courtois G 《Cellular and molecular life sciences : CMLS》2008,65(7-8):1123-1132
CYLD is a protein with tumor suppressor properties which was originally discovered associated with cylindromatosis, an inherited
cancer exclusively affecting the folicullo-sebaceous-apocrine unit of the epidermis. CYLD exhibits deubiquitinating activity
and acts as a negative regulator of NF-κB and JNK signaling through its interaction with NEMO and TRAF2. Recent data suggest
that this is unlikely to be its unique function in vivo. CYLD has also been shown to control other seemingly disparate cellular processes, such as proximal T cell receptor signaling,
TrkA endocytosis and mitosis. In each case, this enzyme appears to act by regulating a specific type of polyubiquitination,
K63 polyubiquitination, that does not result in recognition and degradation of proteins by the proteasome but instead controls
their activity through diverse mechanisms.
Received 6 October 2007; received after revision 2 November 2007; accepted 23 November 2007 相似文献
3.
tRNase Z: the end is not in sight 总被引:1,自引:0,他引:1
Although the enzyme tRNase Z has only recently been isolated, a plethora of data has already been acquired concerning the
enzyme. tRNase Z is the endonuclease that catalyzes the removal of the tRNA 3′ trailer, yielding the mature tRNA 3′ end ready
for CCA addition and aminoacylation. Another substrate cleaved by tRNase Z is the small chromogenic phosphodiester bis(p-nitrophenyl)phosphate (bpNPP), which is the smallest tRNase Z substrate known so far. Hitherto the biological function as
tRNA 3′-end processing enzyme has been shown only in one prokaryotic and one eukaryotic organism, respectively. This review
summarizes the present information concerning the two tRNase Z substrates pre-tRNA and bpNPP, as well as the metal requirements
of tRNase Z enzymes.
Received 29 March 2007; received after revision 15 May 2007; accepted 21 May 2007 相似文献
4.
Jijun Yuan Jessica C. Zweers Jan Maarten van Dijl Ross E. Dalbey 《Cellular and molecular life sciences : CMLS》2010,67(2):179-199
In the three domains of life, the Sec, YidC/Oxa1, and Tat translocases play important roles in protein translocation across
membranes and membrane protein insertion. While extensive studies have been performed on the endoplasmic reticular and Escherichia coli systems, far fewer studies have been done on archaea, other Gram-negative bacteria, and Gram-positive bacteria. Interestingly,
work carried out to date has shown that there are differences in the protein transport systems in terms of the number of translocase
components and, in some cases, the translocation mechanisms and energy sources that drive translocation. In this review, we
will describe the different systems employed to translocate and insert proteins across or into the cytoplasmic membrane of
archaea and bacteria. 相似文献
5.
From a handful of uncloned genetic loci 6 years ago, great strides have been made in understanding the genetic and molecular
aetiology of Bardet-Biedl syndrome (BBS), a rare pleiotropic disorder characterised by a multitude of symptoms, including
obesity, retinal degeneration and cystic kidneys. Presently, 11 BBS genes have been cloned, with the likelihood that yet more BBS genes remain undiscovered. In 2003, a major breakthrough was made when it was shown that BBS is likely caused by defects
in basal bodies and/or primary cilia. Since then, studies in numerous animal models of BBS have corroborated the initial findings
and, in addition, have further refined the specific functions of BBS proteins. These include roles in establishing planar
cell polarity (noncanonical Wnt signaling) in mice and zebrafish, modulating intraflagellar transport and lipid homeostasis
in worms, and regulating intracellular trafficking and centrosomal functions in zebrafish and human tissue culture cells.
From these discoveries, a common theme has emerged, namely that the primary function of BBS proteins may be to mediate and
regulate microtubule-based intracellular transport processes.
Received 20 April 2006; received after revision 30 May 2006; accepted 15 June 2006 相似文献
6.
Jensen MR Hass MA Hansen DF Led JJ 《Cellular and molecular life sciences : CMLS》2007,64(9):1085-1104
Metal ions play a key role for the function of many proteins. The interaction of the metal ion with the protein and its involvement
in the function of the protein vary widely. In some proteins, the metal ion is bound tightly to the ligand residues and may
be the key player in the function of the protein, as in the case of blue copper proteins. In other proteins, the metal ion
is bound only temporarily and loosely to the protein, as in the case of some metalloenzymes and other proteins where the metal
ion acts as a cofactor necessary for the function of the protein. Such proteins are often known as metal ion-activated proteins.
The review focuses on recent nuclear magnetic resonance (NMR) studies of a series of metal-dependent proteins and the characterization
of the metal-binding sites. In particular, we focus on NMR techniques for studying metal binding to proteins such as chemical
shift mapping, paramagnetic NMR and changes in backbone dynamics upon metal binding.
Received 12 October 2006; received after revision 30 November 2006; accepted 5 February 2007 相似文献
7.
Jedrzejas MJ 《Cellular and molecular life sciences : CMLS》2007,64(21):2799-2822
Bacteria present a variety of molecules either on their surface or in a cell-free form. These molecules take part in numerous
processes in the interactions with their host, with its tissues and other molecules. These molecules are essential to bacterial
pathogenesis either during colonization or the spread/invasion stages, and most are virulence factors. This review is focused
on such molecules using Streptococcus pneumoniae, a Gram-positive bacterium, as an example. Selected surface proteins are introduced, their structure described, and, whenever
available, their mechanisms of function on an atomic level are explained. Such mechanisms for hyaluronate lyase, pneumococcal
surface protein A, pneumolysin, histidine-triad and fibronectin-binding proteins are discussed. Elucidation of molecular mechanisms
of virulence factors is essential for the understanding of bacteria and their functional properties. Structural biology appears
pivotal for these studies, as structural and mechanistic insights facilitate rational approach to the development of new treatments.
Received 12 March 2007; received after revision 28 June 2007; accepted 18 July 2007 相似文献
8.
Davies WI Zheng L Hughes S Tamai TK Turton M Halford S Foster RG Whitmore D Hankins MW 《Cellular and molecular life sciences : CMLS》2011,68(24):4115-4132
Melanopsin (OPN4) is an opsin photopigment that, in mammals, confers photosensitivity to retinal ganglion cells and regulates
circadian entrainment and pupil constriction. In non-mammalian species, two forms of opn4 exist, and are classified into mammalian-like (m) and non-mammalian-like (x) clades. However, far less is understood of the function of this photopigment family. Here we identify in zebrafish five
melanopsins (opn4m-1, opn4m-2, opn4m-3, opn4x-1 and opn4x-2), each encoding a full-length opsin G protein. All five genes are expressed in the adult retina in a largely non-overlapping
pattern, as revealed by RNA in situ hybridisation and immunocytochemistry, with at least one melanopsin form present in all
neuronal cell types, including cone photoreceptors. This raises the possibility that the teleost retina is globally light
sensitive. Electrophysiological and spectrophotometric studies demonstrate that all five zebrafish melanopsins encode a functional
photopigment with peak spectral sensitivities that range from 470 to 484 nm, with opn4m-1 and opn4m-3 displaying invertebrate-like
bistability, where the retinal chromophore interchanges between cis- and trans-isomers in a light-dependent manner and remains within the opsin binding pocket. In contrast, opn4m-2, opn4x-1 and opn4x-2
are monostable and function more like classical vertebrate-like photopigments, where the chromophore is converted from 11-cis to all-trans retinal upon absorption of a photon, hydrolysed and exits from the binding pocket of the opsin. It is thought that all melanopsins
exhibit an invertebrate-like bistability biochemistry. Our novel findings, however, reveal the presence of both invertebrate-like
and vertebrate-like forms of melanopsin in the teleost retina, and indicate that photopigment bistability is not a universal
property of the melanopsin family. The functional diversity of these teleost melanopsins, together with their widespread expression
pattern within the retina, suggests that melanopsins confer global photosensitivity to the teleost retina and might allow
for direct “fine-tuning” of retinal circuitry and physiology in the dynamic light environments found in aquatic habitats. 相似文献
9.
Yasuda O Takemura Y Kawamoto H Rakugi H 《Cellular and molecular life sciences : CMLS》2008,65(3):354-358
Aspirin exerts anti-thrombotic action by acetylating and inactivating cyclooxygenase-1, preventing the production of thromboxane
A
2 in platelets. Through this inhibition of platelet function, aspirin is considered as a preventative of ischemic diseases
such as coronary and cerebral infarction. However, many studies have revealed that aspirin has other beneficial actions in
addition to its anti-platelet activity. For example, aspirin may confer some benefit against colorectal cancer. Here, we discuss
the involvement of inflammation in atherosclerosis and how aspirin exerts its beneficial actions in atherosclerotic diseases
and cancer.
Received 30 September 2007; received after revision 31 October 2007; accepted 6 November 2007 相似文献
10.
OSBP (oxysterol-binding protein) and ORPs (OSBP-related proteins) constitute an enigmatic eukaryotic protein family that is
united by a signature domain that binds oxysterols, sterols, and possibly other hydrophobic ligands. The human genome contains
12 OSBP/ORP family members genes, while that of the budding yeast Saccharomyces cerevisiae encodes seven OSBP homologues (Osh). Of these, Osh4 (also referred to as Kes1) has been the most widely studied to date.
Recently, three-dimensional crystal structures of Osh4 with and without sterols bound within the core of the protein were
determined. The core consists of 19 anti-parallel β-sheets that form a near-complete β-barrel. Recent work has suggested that
Osh proteins facilitate the non-vesicular transport of sterols in vivo and in vitro, while other evidence supports a role for Osh proteins in the regulation of vesicular transport and lipid metabolism.This
article will review recent advances in the study of ORP/Osh proteins and will discuss future research issues regarding the
ORP/Osh family.
Received 17 July 2007; received after revision 14 August 2007; accepted 12 September 2007 相似文献
11.
Summary In an effort to determine the number of proteins responsible for the synthesis of the neutral carotenoids inN. crassa, the soluble protein extracts from light-induced and dark-grown cultures of a neurosporaxanthinless strain were compared electrophoretically. The differences relevant to the carotenogenic proteins were identified by reference to an albino polarity mutant. A single, electrophoretically determinable, protein was found to be specific to carotenogenesis. This implication of a single (presumably an enzyme aggregate) protein controlling carotenoid synthesis is discussed and correlated to the existing genetic, complementation and biochemical evidence. 相似文献
12.
Modulation of protein biophysical properties by chemical glycosylation: biochemical insights and biomedical implications 总被引:2,自引:0,他引:2
Solá RJ Rodríguez-Martínez JA Griebenow K 《Cellular and molecular life sciences : CMLS》2007,64(16):2133-2152
Glycosylation constitutes one of the most important posttranslational modifications employed by biological systems to modulate
protein biophysical properties. Due to the direct biochemical and biomedical implications of achieving control over protein
stability and function by chemical means, there has been great interest in recent years towards the development of chemical
strategies for protein glycosylation. Since current knowledge about glycoprotein biophysics has been mainly derived from the
study of naturally glycosylated proteins, chemical glycosylation provides novel insights into its mechanistic understanding
by affording control over glycosylation parameters. This review presents a survey of the effects that natural and chemical
glycosylation have on the fundamental biophysical properties of proteins (structure, dynamics, stability, and function). This
is complemented by a mechanistic discussion of how glycans achieve such effects and discussion of the implications of employing
chemical glycosylation as a tool to exert control over protein biophysical properties within biochemical and biomedical applications.
Received 15 December 2006; received after revision 28 March 2007; accepted 25 April 2007 相似文献
13.
In recent years the interest in antimicrobial proteins and peptides and their mode of action has been rapidly increasing due
to their potential to prevent and combat microbial infections in all areas of life. A detailed knowledge about the function
of such proteins is the most important requirement to consider them for future application. Our research in recent years has
been focused on the low molecular weight, cysteine-rich and cationic antifungal protein PAF from Penicillium chrysogenum, which inhibits the growth of opportunistic zoo-pathogens including Aspergillus fumigatus, numerous plant-pathogenic fungi and the model organism Aspergillus nidulans. So far, the experimental results indicate that PAF elicits hyperpolarization of the plasma membrane and the activation of
ion channels, followed by an increase in reactive oxygen species in the cell and the induction of an apoptosis-like phenotype.
Detailed knowledge about the molecular mechanism of action of antifungal proteins such as PAF contributes to the development
of new antimicrobial strategies that are urgently needed.
Received 09 August 2007; received after revision 17 September 2007; accepted 19 September 2007 相似文献
14.
Fernández MR Porté S Crosas E Barberà N Farrés J Biosca JA Parés X 《Cellular and molecular life sciences : CMLS》2007,64(11):1419-1427
ζ-crystallins constitute a family of proteins with NADPH:quinone reductase activity found initially in mammalian lenses but
now known to be present in many other organisms and tissues. Few proteins from this family have been characterized, and their
function remains unclear. In the present work, ζ-crystallins from human and yeast (Zta1p) were expressed, purified and characterized.
Both enzymes are able to reduce ortho-quinones in the presence of NADPH but are not active with 2-alkenals. Deletion of the ZTA1 gene makes yeast more sensitive to menadione and hydrogen peroxide, suggesting a role in the oxidative stress response. The
human and yeast enzymes specifically bind to adenine-uracil rich elements (ARE) in RNA, indicating that both enzymes are ARE-binding
proteins and that this property has been conserved in ζ-crystallins throughout evolution. This supports a role for ζ-crystallins
as trans-acting factors that could regulate the turnover of certain mRNAs.
Received 21 February 2007; received after revision 16 April 2007; accepted 23 April 2007
M. R. Fernández, S. Porté: These authors contributed equally to this work. 相似文献
15.
Protein-O-mannosyltransferases (Pmt proteins) catalyse the addition of mannose to serine or threonine residues of secretory proteins.
This modification was described first for yeast and later for other fungi, mammals, insects and recently also for bacteria.
O-mannosylation depends on specific isoforms of the three Pmt1, 2 and 4 subfamilies. In fungi, O-mannosylation determines the structure and integrity of cell walls, as well as cellular differentiation and virulence. O-mannosylation of specific secretory proteins of the human fungal pathogen Candida albicans and of the bacterial pathogen Mycobacterium tuberculosis contributes significantly to virulence. In mammals and insects, Pmt proteins are essential for cellular differentiation and
development, while lack of Pmt activity causes Walker-Warburg syndrome (muscular dystrophy) in humans. The susceptibility
of human cells to certain viruses may also depend on O-mannosyl chains. This review focuses on the various roles of Pmt proteins in cellular differentiation, development and virulence.
Received 6 September 2007; received after revision 3 October 2007; accepted 5 October 2007 相似文献
16.
Molecular mechanisms of nitrosative stress-mediated protein misfolding in neurodegenerative diseases
Nitrosative and oxidative stress, associated with the generation of excessive reactive oxygen or nitrogen species, are thought
to contribute to neurodegenerative disorders. Many such diseases are characterized by conformational changes in proteins that
result in their misfolding and aggregation. Accumulating evidence implies that at least two pathways affect protein folding:
the ubiquitin-proteasome system (UPS) and molecular chaperones. Normal protein degradation by the UPS can prevent accumulation
of aberrantly folded proteins. Molecular chaperones – such as protein-disulfide isomerase, glucose-regulated protein 78, and
heat shock proteins – can provide neuroprotection from aberrant proteins by facilitating proper folding and thus preventing
their aggregation. Our recent studies have linked nitrosative stress to protein misfolding and neuronal cell death. Here,
we present evidence for the hypothesis that nitric oxide contributes to degenerative conditions by S-nitrosylating specific chaperones or UPS proteins that would otherwise prevent accumulation of misfolded proteins.
Received 5 December 2006; received after revision 7 February 2007; accepted 15 March 2007 相似文献
17.
Cell adhesion molecules (CAMs) have been implicated in the control of a wide variety of cellular processes, such as cell adhesion,
polarization, survival, movement, and proliferation. Nectins have emerged as immunoglobulin-like CAMs that participate in
calcium-independent cell-cell adhesion by homophilic and heterophilic trans-interactions with nectins and nectin-like molecules. Nectin-based cell-cell adhesion exerts its function independently or
in cooperation with other CAMs including cadherins and is essential for the formation of intercellular junctions, including
adherens junctions, tight junctions, and puncta adherentia junctions. Nectins cis-interact with integrin αvβ3 and platelet-derived growth factor receptor and facilitate their signals to regulate the formation and integrity of intercellular
junctions and cell survival. Nectins intracellularly associate with peripheral membrane proteins, including afadin and Par-3.
This review focuses on recent progress in understanding the interactions of nectins with other transmembrane and peripheral
membrane proteins to exert pleiotropic functions.
Received 27 June 2007; received after revision 14 August 2007; accepted 12 September 2007 相似文献
18.
This review covers recent findings concerning the specification of the photoreceptor subtypes in the Drosophila eye. Particular attention is paid to aspects of retinal patterning and differentiation where relative timing of events seems to be tightly controlled and essential for proper assembly of the compound eye. For example, specification of the founding photoreceptors of each cluster requires sequential positive and negative signaling through the Notch pathway, and reiterated signaling through the epidermal growth factor receptor leads to the pairwise recruitment of the distinct types of photoreceptors in discrete zones across the eye. Results suggest that different signaling environments for these two receptors may exist across the disc, and that receiving cells may constantly shift their predisposition to respond to such signals by adopting given fates. In addition, considerable data exist that the rate of expansion of retinal patterning across the disc is restricted to allow the orderly patterning of retinal precursors, and that one mechanism for controlling this rate may be the co-ordinated expression anterior to the furrow of factors which both inhibit and promote the expansion of retinal patterning. Finally, this review considers the possibility that the morphogenetic furrow serves as a moving source of morphogens which supply spatial information to both anterior and posterior tissue, providing temporal cues that regulate the many events involved in orderly assembly of the precise array of retinal cell types in the compound eye. 相似文献
19.
Summary The pineal of lower vertebrates characteristically contains true and modified photoreceptors with functional und structural homologies to retinal photoreceptors. Afferent nerves convey photic information from the pineal to sensory areas of the brain stem. Light also influences synthetic activity within the organ, controlling the rhythm in melatonin production which is generated endogenously. The molecular mechanisms underlying this rhythmic event are described and the hypothesis advanced that the pineal transduces several forms of environmental stimulus involved in the regulation of rhythmic function. 相似文献
20.
The aquaporin protein family generally seems to be designed for the selective passage of water or glycerol. Charged molecules,
metal ions and even protons are strictly excluded. Recently, particular aquaporin isoforms were reported to conduct unconventional
permeants, i.e., the unpolar gases carbon dioxide and nitric oxide, the polar gas ammonia, the oxidative oxygen species hydrogen peroxide,
and the metalloids antimonite, arsenite and silicic acid. Here, we summarize the available data on permeability properties
and physiological settings of these aquaporins and we analyze which structural features might be connected to permeability
for non-water, non-glycerol solutes.
Received 31 March 2007; received after revision 3 May 2007; accepted 23 May 2007 相似文献