ISSN:1065-6995    

DOI:10.1006/cbir.1994.1077

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTThe role of rapidly exchanging intracellular Ca2+stores in the control of Ca2+homeostasis is reviewed. The following issues are discussed: the reasons why such stores exist in eukaryotic cells; the differences between the terminal cisternae of the skeletal muscle sarcoplasmic reticulum, which have direct, physical connection with the T tubules of the plasmalemma, and the Ca2+stores located in the depth of the cytoplasm, which are stimulated by second messengers; the cytological nature (subcompartments of the ER) of the rapidly exchanging Ca2+stores and their functional significance. The conclusions introduce recent developments in which intracellular Ca2+stores have been investigated also by molecular biology techniques.

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1078

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTThe distribution of microtubule‐associated protein lB (MAPlB) phosphorylated by either proline‐directed protein kinase (PDPK) or casein kinase II (CK II) in neuroblastoma cells and hippocampal neurons has been studied by immunofluorescence using specific antibodies to distinct phosphorylation‐sensitive epitopes. A proximo‐distal gradient of increasing PDPK‐catalyzed phosphorylation of MAPlB is superimposed on a proximo distal gradient of decreasing CK II‐catalyzed MAPlB phosphorylation within growing axon‐like neurites. Additionally, CK II‐phosphorylated MAPlB is present in cell bodies and dendrites where no PDPK‐phosphorylated MAPlB is observed. These results suggest distinct roles for both types of modifications of MAPlB in d

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1079

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTThe role of the measles virus (MV) receptor, human CD46, in the uptake of MV and antigen presentation by Major Histocompatibility Complex (MHC) class II molecules was investigated. Expression of CD46 in murine B cells resulted in cells highly efficient in capturing UV‐inactivated MV particles and presenting both envelope hemagglutinin H and nucleoprotein N to specific T cell hybridomas. Although MV fuse with the plasma membrane of its target cells, presentation of both MV‐H and ‐N was sensitive to inhibition by chloroquine but was not affected by a tripeptide which prevents virus‐cell fusion. Whereas 50 μM of chloroquine was required to inhibit presentation of MV‐H, purified H or soluble N, only a two‐fold lower concentration was required to inhibit that of MV‐N. This shows that some CD46‐mediated captured MV particles are endocytosed, then disrupted and processed in an endosome/lyso

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1080

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTA typical feature of epithelial cells is the polarized distribution of their respective plasma membrane proteins. Apical and basolateral proteins can be sorted both in the trans‐Golgi network and endosomes, or in both locations. Inclusion into basolateral carriers in the TGN requires the presence of distinct cytoplasmic determinants, which also appear to be recognized in endosomes. Inactivation of the basolateral sorting information leads to the efficient apical delivery, probably due to the unmasking of a recessive apical signal. Factors associated with the cytosolic face of organelles probably not only recognize these signals to mediate the inclusion of the proteins into the correct transport vesicles, but also target the carriers to the corresponding plasma membrane domain. Our interest has focused on analyzing at the molecular level how epithelial MDCK cells generate and maintain a polarized phenotype, taking advantage of immunoglobulin receptors to study the biosynthetic and endocytic pathways and the corresponding sorting event

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1081

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTDistinct mechanisms operate in different secreting systems, they are 1) free diffusion through the plasma membrane; 2) exocytosis resulting from fusion of a secretory granule with the plasma membrane; 3) fleeting release from a granule through a transient pore without full fusion; 4) release through a specialised plasmalemmal molecule such as the mediatophore. The latter mechanism is proposed to operate in rapid synapses in which the neurotransmitter is emitted as an abrupt chemical impulse of quantal composition. There, release is momentarily signalled in the plasma membrane by large intramembrane particles. Synaptic vesicles are also essential for regulation of this type of release. They fuse with the plasma membrane only late after activity and seem to be involved in calcium sequestration and extrusion.

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1082

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTThe peripheral non‐receptor tyrosine kinase oncoprotein, v‐Src, has pleiotropic effects. It is a mitogen for quiescent cells, substituting for both competence and progression factor‐mediated signals but it also induces cellular morphological transformation. We are dissecting the activities of v‐Src by studying mutant proteins, including those with temperature sensitive (ts) effects, in different cellular backgrounds. Activation of atsv‐Src kinase rapidly increases activity of both the transcription factor, AP‐1, and MAP kinase, an enzyme that enhances AP‐1 activity by both phosphorylation of c‐Jun and increased c‐fostranscription; the relative contribution of these two events depends on the cells in which v‐Src is expressed. Transient early AP‐1 activation requires proper location of v‐Src at the cell periphery and it is essential for mitogenesis. It is not, however, sufficient for entry into S‐phase, there being a second need for v‐Src later in G1. Transformation by v‐Src does not require AP‐1 activation but seems linked to events at the cell periphery, notably phosphorylation of proteins that bind to the v‐Src SH3 domain such

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1083

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

ABSTRACTProton pumping heme‐copper oxidases represent the terminal, energy‐transfer enzymes of respiratory chains in prokaryotes and eukaryotes. The CuB‐heme a3(or heme o) binuclear center, associated with the largest subunit I of cytochrome c and quinol oxidases, is directly involved in the coupling between dioxygen reduction and proton pumping. The role of the other subunits is less clear. The following aspects will be covered in this paper:i) the efficiency of coupling in the mitochondrial aa3cytochrome c oxidase. In particular, the effect of respiratory rate and protonmotive force on the H+/e−stoichiometry and the role of subunit IV; ii) mutational analysis of the aa3quinol oxidase of Bacillus subtilis addressed to the role of subunit III, subunit IV and specific residues in subunit I; iii) possible models of the protonmotive catalytic cycle at the binuclear center. The observations available suggest that H+/e−coupling is based on the combination of protonmotive redox catalysis at the binuclear center and co‐operative proton transfer in

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1084

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1085

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:1065-6995    

DOI:10.1006/cbir.1994.1086

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY