ISSN:0892-6638    

DOI:10.1096/fasebj.7.9.8330677

出版商:Wiley    

年代:1993

数据来源: WILEY

ISSN:0892-6638    

DOI:10.1096/fasebj.7.9.8330678

出版商:Wiley    

年代:1993

数据来源: WILEY

ISSN:0892-6638    

DOI:10.1096/fasebj.7.9.8330679

出版商:Wiley    

年代:1993

数据来源: WILEY

ISSN:0892-6638    

DOI:10.1096/fasebj.7.9.8330680

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

Extracellular matrix (ECM) is an intricate network composed of an array of macromolecules, the importance of which is becoming increasingly apparent. The ECM is an integral part of the machinery that regulates cell function; its role in cell differentiation and tissue‐specific gene expression, although essential, is not yet understood. It can act as a positive as well as a negative regulator of functional differentiation depending on the cell type and the genes studied. It also acts in a hierarchical fashion, exacting higher and higher degrees of stringency to achieve full functional differentiation. Regulation by ECM is closely interrelated with the action of other regulators of cellular function, such as growth factors and hormones. But ECM may exert its regulation of gene expression by mechanisms distinct from those known for soluble transcription factors. In this short review, we describe three systems in which ECM has been shown to play a crucial role in functional differentiation, but we emphasize mainly the work from our own laboratory to provide a more in‐depth analysis of one system. The three systems are: mouse mammary epithelial cells, rat hepatocytes, and human keratinocytes. The crucial role of ECM in normal cell differentiation implies that its alteration may have serious consequences in malignancies and other diseases. The current functional cell culture models could provide powerful tools not only for understanding regulation of normal cell function but also for the studies of tumorigenesis and possibly cancer therapy.—Lin, C. Q., Bissell, M.J. Multi‐faceted regulation of cell differentiation by extracellular matrix.FASEB J. 7:737‐743; 1993.

ISSN:0892-6638    

DOI:10.1096/fasebj.7.9.8330681

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

The ability to use proteins in nonnatural environments greatly expands their potential applications in biotechnology. Because nature has not paid much attention to optimizing proteins for in vitro applications under conditions that differ substantially from their natural surroundings, there is generally room for improvement through alterations in the amino acid sequence. The most effective approach to this protein engineering task depends on the level to which the molecular basis for the desired property is understood. Consistently successful “rational” design using site‐directed mutagenesis requires a high level of understanding of structure and mechanisms or, alternatively, a particularly simple strategy for obtaining the desired feature. An example of a generally applicable and easy‐to‐implement protein stabilization strategy is metal ion chelation by specific surface dihistidine sites, which can affect thermal stability as well as the protein's ability to withstand denaturants such as guanidinium chloride. Random mutagenesis, on the other hand, can be effective even when structure or mechanisms are poorly understood, provided one can conveniently screen or select for the property of interest. This approach is illustrated by the sequential accumulation of random mutations that greatly enhance the catalytic activity of a serine protease, subtilisin E, in polar organic solvents. The random mutagenesis approach, which mimics the natural evolutionary refinement process, can be used to “coax” enzymes into tolerating nonnatural environments.—Arnold, F. H. Engineering proteins for nonnatural environments.FASEB J. 7:744‐749; 1993.

ISSN:0892-6638    

DOI:10.1096/fasebj.7.9.8330682

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

TheRassuperfamily of GTP‐binding proteins (>50 members) regulates a diverse spectrum of intracellular processes. These include cellular proliferation and differentiation, intracellular vesicular trafficking, cytoskeletal control, NADPH oxidase function, as well as others. In this review, we describe recent progress and emerging themes in the action and regulation of these important cellular regulatory molecules. Structural studies have provided insight into the function of low molecular weight GTP‐binding proteins (LMWGs) as molecular switches, and are defining modes of interaction with associated regulatory molecules. Details of the enzymatic processes involved in the posttranslational processing of LMWGs, and how this processing is important for protein function, are being elucidated. A variety of GTPase activating proteins, GDP/GTP dissociation stimulators, and GDP dissociation inhibitors have been identified, and their ability to determine the activity of LMWG‐regulated systems is being worked out. The discovery of multifunctional regulatory molecules has indicated that substantial “crosstalk” between various LMWG may occur. The continuing emergence of additional cellular functions that are regulated by LMWGs, and particularly the recent availability of in vitro analytical systems for studies of the mechanism (or mechanisms) of action of LMWGs, is resulting in a wealth of information about the regulation and integration of cellular signaling, form, and function.—Bokoch, G. M., Der, C. J. Emerging concepts in theRassuperfamily of GTP‐binding proteins.FASEB J. 7:750‐759; 1993.

ISSN:0892-6638    

DOI:10.1096/fasebj.7.9.8330683

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

Genetic recombination plays a key role in the life of organisms as diverse as bacteriophages and humans. Contrary to our idea that chromosomes are stable structures, studies of recombination over the past few decades have shown that in fact DNA replicons are remarkably plastic, undergoing frequent recombination‐induced rearrangements. This review summarizes our recent knowledge of the biochemistry of the two major classes of site‐specific recombination:1) transpositional recombination, and2) conservative site‐specific recombination.—Sadowski, P. D. Site‐specific genetic recombination: hops, flips, and flops.FASEB J. 7:760‐767; 1993.

ISSN:0892-6638    

DOI:10.1096/fasebj.7.9.8392474

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

Receptor‐regulated adenylyl cyclase in mammalian systems is among the best‐studied of the cell surface signaling pathways that utilize G‐proteins as transducers. In addition to the multiplicity of receptors and Gsproteins that function in this pathway, recent studies have shown that substantial molecular diversity exists in the effector as well. Full‐length cDNAs encoding six different G‐protein‐regulated adenylyl cyclases have been isolated, and partial sequences identifying two more are known. These eight mammalian adenylyl cyclases can be grouped into five distinct families. The different types share some common properties such as stimulation by Gsand the diterpene forskolin. They show very distinct patterns of regulation by the βγ‐subunits of G‐proteins and protein kinases such as protein kinase C. The different types also appear to be localized in a tissue‐specific manner. This diversity of regulatory features indicates that the effector can play an important role in determining the routing of signals to the cAMP pathway. The tissue and cell type‐specific localization of the individual forms suggests that effectors such as adenylyl cyclase could be potential targets for a new generation of cell and tissue‐specific drugs.—Iyengar, R. Molecular and functional diversity of mammalian Gs‐stimulated adenylyl cyclases.FASEB J. 7:768‐775; 1993.

ISSN:0892-6638    

DOI:10.1096/fasebj.7.9.8330684

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

Identification of O‐phosphorylated amino acids within the primary structure of regulatory proteins is important in understanding the mechanisms by which their functions are regulated. In many cases radioactive labeling with [32P]phosphate is tedious or sometimes impossible. Therefore, we have established a series of new non‐radioactive methods that permit the localization of phosphoserine, phosphothreonine, and phosphotyrosine. After partial hydrolysis of a phosphopeptide or phosphoprotein, phosphoserine, phosphothreonine, or phosphotyrosine are determined by capillary electrophoresis as their dabsyl‐derivatives. Chemical modification transforms phosphoserine or phosphothreonine to S‐ethylcysteine or β‐methyl‐S‐ethyl‐cysteine, respectively, allowing their localization during sequence analysis. We apply solid‐phase sequencing to overcome the limitations of the gas‐phase sequenator in the case of phosphotyrosinecontaining peptides. Liquid chromatography on‐line connected to an electrospray mass spectrometer is a powerful new method of increasing importance in the protein chemistry field. It is especially well suited for identification of phosphoserine‐ or phosphothreonine‐containing peptides in a proteolytic digest of a phosphoprotein. In this article we will describe how to work with these new methods practically.—Meyer, H. E., Eisermann, B., Heber, M., Hoffmann‐Posorske, E., Korte, H., Weigt, C., Wegner, A., Hutton, T., Donella‐Deana, A., Perich, J. W. Strategies for nonradioactive methods in the localization of phosphorylated amino acids in proteins.FASEB J. 7:776‐782; 1993.

ISSN:0892-6638    

DOI:10.1096/fasebj.7.9.7687226

出版商:Wiley    

年代:1993

数据来源: WILEY