摘要:

AbstractActin is a protein that plays an important role in cell structure, cell motility, and the generation of contractile force in both muscle and nonmuscle cells. In many organisms, multiple forms of actin, or isoactins, are found. These are products of different genes and have different, although very similar, amino acid sequences. Furthermore, these isoactins are expressed in a tissue specific fashion that is conserved across species, suggesting that their presence is functionally important and their behavior can be distinguished quantitatively from one anotherin vitro. In muscle cells, they are differentially distributed within the cell and some are specifically associated with structures such as costameres, mitochondria, and neuromuscular junctions. There is also good evidence for specific isoactin function in microvascular pericytes and in the intestinal brush border. However, the necessity of specific isoactins for various functions has not yet been conclusively demonstrated.

ISSN:0265-9247    

DOI:10.1002/bies.950120702

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

年代:1990

数据来源: WILEY

摘要:

AbstractIntroduction of human plasma protein genes into the mouse genome to produce transgenic mice furnishes anin vivomodel for correlating chromosomal DNA sequences with developmental and tissue‐specific expression. The liver produces an array of plasma proteins that circulate throughout the body contributing to homeostasis. Non‐hepatic tissue sites of synthesis have been identified where a local provision of plasma proteins in needed. Analysis of expression of human plasma protein genes in ageing transgenic mice appears especialy promising in identifying DNA sequences that respond to environmental adversities such as inflammatory factors, hormonal changes and metal toxicity. The results indicate that human genes encoding and controlling liver plasma proteins serve as useful models for studying genetic regulation in the background of development and age

ISSN:0265-9247    

DOI:10.1002/bies.950120703

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

年代:1990

数据来源: WILEY

摘要:

AbstractThe double membrane of the nuclear envelope is a formidable barrier separating the nucleus and cytoplasm of eukaryotic cells. However, movement of specific macromolecules across the nuclear envelope is critical for embryonic development, cell growth and differentiation. Transfer of molecules between the nucleus and cytoplasm occurs through the aqueous channel formed by the nuclear pore complex (NPC)Abbreviations: NPC, nuclear pore complex; GlcNac, N‐acetylglucosamine; WGA, wheat germ agglutinin. Although small molecules may simply diffuse across the NPC, transport of large proteins and RNA requires specific transport signals and is energy dependent. A family of pore glycoproteins modified byO‐linked N‐acetylglucosamine moieties are essential for transport through the NPC. Recent evidence suggests that the regulation of nuclear transport may also involve the inteaction of RNA and nuclear proteins with specific binding proteins that recognize these transport signals. Are these nuclear pore glycoproteins and signal binding proteins the ‘gatekeepers’ that control access to the genetic material? Recent evidence obtained from a combination of biochemical and genetic approaches suggests

ISSN:0265-9247    

DOI:10.1002/bies.950120704

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

年代:1990

数据来源: WILEY

摘要:

AbstractInborn errors of vitamin B12(cobalamin) metabolism are associated with homocystinuria and methylmalonic aciduria, either alone or in combination. A number of these disorders have provided the first evidence for the existence of important steps in the transport or metabolism of cobalamin in eukaryotic cells. Eight complementation classes have been defined on the basis of somatic cell hybridization studies. Although the majority of patients present in infancy or early childhood, some are not diagnosed until adolescence or later. For some of these disorders, prenatal diagnosis and therapy with cobalamin during pregnancy has been attempted. Although only males have been described with cblE disease, all of these disorders are presumed to be autosomal recessive in inheritance. The clinical and laboratory aspects of the different complementation classes (cblA–cblG) are reviewed her

ISSN:0265-9247    

DOI:10.1002/bies.950120705

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

年代:1990

数据来源: WILEY

摘要:

AbstractMethylmalonyl CoA mutase deficiency (methylmalonic acidemia) has been a paradigm for biochemical and somatic cell genetic approaches to human disease. Recently, genes encoding this enzyme have been cloned from several species. These studies have provided information about the primary structure and evolution of this enzyme, the mutations which underlie its deficiency state, and the structure‐function determinants which are required for its activity. Gene transfer studies now permit restitution of this enzyme to genetically deficient cells and may enable somatic gene therapy to be undertaken. Molecular genetic studies not only provide more detailed information about this enzyme, but introduce new perspectives on the molecular mechanisms and dynamics of its function and raise new questions about the dyshomeostatic consequences of its deficienc

ISSN:0265-9247    

DOI:10.1002/bies.950120706

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

年代:1990

数据来源: WILEY

ISSN:0265-9247    

DOI:10.1002/bies.950120707

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

年代:1990

数据来源: WILEY

ISSN:0265-9247    

DOI:10.1002/bies.950120708

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

年代:1990

数据来源: WILEY

ISSN:0265-9247    

DOI:10.1002/bies.950120709

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

年代:1990

数据来源: WILEY

ISSN:0265-9247    

DOI:10.1002/bies.950120710

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

年代:1990

数据来源: WILEY

ISSN:0265-9247    

DOI:10.1002/bies.950120711

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

年代:1990

数据来源: WILEY