摘要:

AbstractThe viral and cellular forms of the Src protein tyrosine kinases take a prototypic role in oncology and signal transduction research, by virtue of being holders of an impressive number of ‘firsts’. Our understanding of the biochemistry and physiology of Src has therefore always been used as a reference for our general advancement in the field of protein phosphorylation and growth control. The recent solution of the crystal structure of two members of the Src family(1,2)represents a milestone in these disciplines and, as usual, provides a general lookout post for developments to c

ISSN:0265-9247    

DOI:10.1002/bies.950190602

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

摘要:

AbstractMicrotubules are organized into diverse cellular structures in multicellular organisms. How is such diversity generated? Although highly conserved overall, variable regions within α‐ and β‐tubulins show divergence from other α‐ and β‐tubulins in the same species, but show conservation among different species. Such conservation raises the question of whether diversity in tubulin structure mediates diversity in microtubule organization. Recent studies probing the function of β‐tubulin isotypes in axonemes of insects(1)suggest that tubulin structure, through interactions with extrinsic proteins, can direct the architecture and supramolecular organization o

ISSN:0265-9247    

DOI:10.1002/bies.950190603

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

摘要:

AbstractClp ATPase chaperone proteins are found in procaryotes and eucaryotes. Recently, ClpC ofBacillus subtiliswas found to be part of a regulatory switch(1). ClpC, in combination with the MecA and ComS proteins, regulates the activity of a transcription factor, ComK, which is necessary for the development of genetic competence (the ability to bind and take up exogenous DNA). The complex of ClpC:MecA:ComK renders ComK inactive. Interaction between ComS and the ternary complex releases active ComK. This regulatory switch controls ComK activity in response to cell density signals that affect production of ComS. Regulated interaction between Clp ATPases and target proteins might prove to be widespread.

ISSN:0265-9247    

DOI:10.1002/bies.950190604

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

摘要:

AbstractEvery cartilage and bone in the vertebrate skeleton has a precise shape and position. The head skeleton develops in the embryo from the neural crest, which emigrates from the neural ectoderm and forms the skull and pharyngeal arches. Recent genetic data from mice and zebrafish suggest that cells in the pharyngeal segments are specified by positional information in at least two dimensions,Hoxgenes along the anterior‐posterior axis and other homeobox genes along the dorsal‐ventral axis within a segment. Many zebrafish and human mutant phenotypes indicate that additional genes are required for the development of groups of adjacent pharyngeal arches and for patterning along the mediolateral axis of the skull. The complementary genetic approaches in humans, mice and fish reveal networks of genes that specify the complex morphology of the head skeleton along a relatively simple set of coordina

ISSN:0265-9247    

DOI:10.1002/bies.950190605

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

摘要:

AbstractPDZ (also called DHR or GLGF) domains are found in diverse membraneassociated proteins including members of the MAGUK family of guanylate kinase homologues, several protein phosphatases and kinases, neuronal nitric oxide synthase, and several dystrophin‐associated proteins, collectively known as syntrophins. Many PDZ domain‐containing proteins appear to be localised to highly specialised submembranous sites, suggesting their participation in cellular junction formation, receptor or channel clustering, and intracellular signalling events. PDZ domains of several MAGUKs interact with the C‐terminal polypeptides of a subset of NMDA receptor subunits and/or with Shaker‐type K+channels. Other PDZ domains have been shown to bind similar ligands of other transmembrane receptors. Recently, the crystal structures of PDZ domains, with and without ligand, have been determined. These demonstrate the mode of ligand‐binding and the structural bases for sequence conservation among diverse PD

ISSN:0265-9247    

DOI:10.1002/bies.950190606

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

摘要:

AbstractThe mammalian dentition is a segmented organ system with shape differences among its serially homologous elements (individual teeth). It is believed to have evolved from simpler precursors with greater similarities in shape among teeth, and a wealth of descriptive data exist on changes to the dentition that have occurred within mammals. Recent progress has been made in determining the genetic basis of the processes that form an individual tooth, but patterning of the dentition as a whole (i.e. the number, location and shape of the teeth) is less well understood. In contrast to similarly organized systems, such as the vertebral column and limb, Hox genes are not involved in specifying differences among elements. Nevertheless, recent work on a variety of systems is providing clues to the transcription factors and extracellular signalling molecules involved.

ISSN:0265-9247    

DOI:10.1002/bies.950190607

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

摘要:

AbstractThe discovery of the first intracellular substrate for insulin, IRS‐1, redirected the field of diabetes research and has led to many important advances in our understanding of insulin action. Detailed analysis of IRS‐1 demonstrates structure/function relationships for this modular docking molecule, including mechanisms of substrate recognition and signal propagation. Recent work has also identified other structurally similar molecules, including IRS‐2, the Drosophila protein, DOS, and the Grb2‐binding protein, Gab1, suggesting that this intracellular signalling strategy is conserved evolutionarily and is utilized by an expanding number of receptor systems. In fact, IRS‐1 itself has been shown to be important in other growth factor and cytokine signalling systems, including growth hormone and several interleukins. Analysis of mice lacking IRS‐1 confirms an important physiological role for this protein in glucose metabolism and general cell growth in the intact animal. Disregulation of the signalling pathways integrated by the IRS proteins may contribute to the pathophysiology of non‐insulin‐dependent diabetes mellitus or

ISSN:0265-9247    

DOI:10.1002/bies.950190608

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

摘要:

AbstractInterleukin 1β‐converting enzyme (ICE)‐like proteases (caspases) play an important role in programmed cell death (apoptosis), and elucidating the consequences of their proteolytic activity is central to our understanding of the molecular mechanisms of cell death. Diverse structural and regulatory proteins and enzymes, including protein kinase Cδ, the retinoblastoma protein (a protein involved in cell survival), the DNA repair enzyme DNA‐dependent protein kinase and the nuclear lamins, undergo specific and limited endoproteolytic cleavage by various caspases during apoptosis. Since individual caspases can cleave multiple substrates, the consequences of cleavage of only a single substrate are still poorly understood. Nevertheless, proteolytic activation of protein kinase Cδ may be an important early step in the cell death pathway, and cleavage of the retinoblastoma protein could suppress its cell survival function, whereas proteolytic inactivation of DNA repair enzymes might compromise the ability of the cell to reverse DNA fragmentation. On the other hand, cleavages of nuclear and cytoplasmic structural proteins (e.g. the lamins and Gas2) appear to be required for or contribute to the dramatic rearrangements in cellular architecture that are necessary for the completion of the cell death process. An emerging theme is that parallel and sequential proteolytic activation and inactivation of key protein substrates occurs during the multiple steps of a

ISSN:0265-9247    

DOI:10.1002/bies.950190609

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

摘要:

AbstractCollections are a group of multimeric proteins mostly consisting of 9–18 polypeptides organised into either ‘bundle‐of‐tulips’ or ‘X‐like’ overall structures. Each polypeptide contains a short N‐terminal segment followed by a collagen‐like sequence and then by a C‐terminal lectin domain. A collectin molecule is assembled from identical or very similar polypeptides by disulphide bonds at the N‐terminal segment, formation of triple helices in the collagen‐like region and clusters of three lectin domains at the peripheral ends of triple helices. These proteins can bind to sugar residues on microorganismsviathe peripheral lectin domains and subsequently interact,viathe collagen‐like triple‐helices, with receptor(s) on phagocytes and/or the complement system to bring about the killing and clearance of the targets without the involvement of antibodies. The collectins can also bind to phagocyte receptor(s) to enhance phagocytosis mediated by other phagocytic receptors. Lack, or low levels, of collectin expression can lead to higher susceptibility to infections, especially during childhood when specific immunity has not fully developed. Therefore, the collectins play important roles in the e

ISSN:0265-9247    

DOI:10.1002/bies.950190610

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY

摘要:

AbstractThe plastic response of phenotypic traits to environmental change is a common research focus in several disciplines ‐ from ecology and evolutionary biology to physiology and molecular genetics. The use of model systems such as the flowering plantArabidopsis thalianahas facilitated a dialogue between developmental biologists askinghowplasticity is controlled (proximate causes) and organismal biologists askingwhyplasticity exists (ultimate causes). Researchers studying ultimate causes and consequences are increasingly compelled to reject simplistic, ‘black box’ models, while those studying proximate causes and mechanisms are increasingly obliged to subject their interpretations to ecological ‘reality checks.’ We review the successful multidisciplinary efforts to understand the phytochrome‐mediated shade‐avoidance and light‐seeking responses of flowering plants as a pertinent example of convergence between evolutionary and molecular biology. In this example, the two‐way exchange between reductionist and holist camps has been essential to rapid and sustained progress. This should serve as a model for future collaborative efforts towards understanding the responses of organisms to their constantly chan

ISSN:0265-9247    

DOI:10.1002/bies.950190611

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1997

数据来源: WILEY