The Na+/H+ antiport of eukaryotic cells: Relationship between the kinetic properties of the system and its physiological function

Biochimie ◽  
1986 ◽  
Vol 68 (12) ◽  
pp. 1279-1285 ◽  
Author(s):  
Christian Frelin ◽  
Pascal Barbry ◽  
Richard D. Green ◽  
Thierry Jean ◽  
Paul Vigne ◽  
...  
Keyword(s):  
Physiological Function ◽  
Eukaryotic Cells ◽  
Kinetic Properties

scholarly journals The liverwort oil body is formed by redirection of the secretory pathway

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Takehiko Kanazawa ◽  
Hatsune Morinaka ◽  
Kazuo Ebine ◽  
Takashi L. Shimada ◽  
Sakiko Ishida ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transcription Factor ◽  
Secretory Pathway ◽  
Physiological Function ◽  
Eukaryotic Cells ◽  
Marchantia Polymorpha ◽  
Oil Body ◽  
Body Formation ◽  
Common Strategy

AbstractEukaryotic cells acquired novel organelles during evolution through mechanisms that remain largely obscure. The existence of the unique oil body compartment is a synapomorphy of liverworts that represents lineage-specific acquisition of this organelle during evolution, although its origin, biogenesis, and physiological function are yet unknown. We find that two paralogous syntaxin-1 homologs in the liverwort Marchantia polymorpha are distinctly targeted to forming cell plates and the oil body, suggesting that these structures share some developmental similarity. Oil body formation is regulated by an ERF/AP2-type transcription factor and loss of the oil body increases M. polymorpha herbivory. These findings highlight a common strategy for the acquisition of organelles with distinct functions in plants, via periodical redirection of the secretory pathway depending on cellular phase transition.

scholarly journals Switching secretory pathway direction for organelle acquisition in plants

2020 ◽  
Author(s):  
Takehiko Kanazawa ◽  
Hatsune Morinaka ◽  
Kazuo Ebine ◽  
Takashi L. Shimada ◽  
Sakiko Ishida ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transcription Factor ◽  
Secretory Pathway ◽  
Physiological Function ◽  
Eukaryotic Cells ◽  
Marchantia Polymorpha ◽  
Oil Body ◽  
Body Formation ◽  
Common Strategy

AbstractEukaryotic cells acquired novel organelles during evolution through mechanisms that remain largely obscure. The existence of the unique oil body compartment is a synapomorphy of liverworts that represents lineage-specific acquisition of this organelle during evolution, although its origin, biogenesis, and physiological function are yet unknown. We found that two Syntaxin 1 paralogs in the liverwort, Marchantia polymorpha, are distinctly targeted to forming cell plates and the oil body, suggesting these structures share some developmental similarity. Oil body formation is under the regulation of an ERF/AP2-type transcription factor and loss of the oil body increased M. polymorpha herbivory. These findings highlight a common strategy for the acquisition of organelles with distinct functions in plants, via periodical switching in secretion direction depending on cellular phase transition.

scholarly journals Isolation and characterization of pigeon breast muscle cytosolic 5'-nucleotidase-I (cN-I).

2005 ◽  
Vol 52 (4) ◽  
pp. 789-796 ◽  
Author(s):  
Kinga Tkacz-Stachowska ◽  
Katarzyna Lechward ◽  
Andrzej C Skladanowski
Keyword(s):  
Physiological Function ◽  
Specific Activity ◽  
Heart Tissue ◽  
Breast Muscle ◽  
Kinetic Properties ◽  
Type I ◽  
Isolation And Characterization ◽  
Atp Breakdown ◽  
Wet Weight

5'-Nucleotidase specific towards dCMP and AMP was isolated from avian breast muscle and characterized. It was found to be similar to a type-I form (cN-I) identified earlier as the AMP-selective 5'-nucleotidase responsible for adenosine formation during ATP breakdown in transfected COS-7 cells. Expression pattern of the cN-I gene in pigeon tissues indicated breast muscle as a rich source of the transcript. We purified the enzyme from this source using two-step chromatography and obtained an active homogenous preparation, free of ecto-5'-nucleotidase activity. The tissue content of the activity was calculated at 0.09 U/g wet weight. The specific activity of the enzyme preparation was 4.33 U/mg protein and it preferred dCMP and AMP to dAMP and IMP as a substrate. Its kinetic properties were very similar to those of the enzyme purified earlier from heart tissue. It was strongly activated by ADP. Inhibition by inorganic phosphate was more pronounced than in heart-isolated cN-I. Despite this difference, a similar physiological function is suggested for cN-I in both types of muscle.

scholarly journals Novel Type of Glucose-6-Phosphate Isomerase in the Hyperthermophilic Archaeon Pyrococcus furiosus

2001 ◽  
Vol 183 (11) ◽  
pp. 3428-3435 ◽  
Author(s):  
Thomas Hansen ◽  
Margitta Oehlmann ◽  
Peter Schönheit
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Physiological Function ◽  
Pyrococcus Furiosus ◽  
Single Type ◽  
Kinetic Properties ◽  
Significant Similarity ◽  
Reading Frame ◽  
Hyperthermophilic Archaeon ◽  
Terminal Amino

ABSTRACT Glucose-6-phosphate isomerase (phosphoglucose isomerase [PGI]) (EC 5.3.1.9 ) from the hyperthermophilic archaeon Pyrococcus furiosus was purified 500-fold to homogeneity. The enzyme had an apparent molecular mass of 43 kDa and was composed of a single type of subunit of 23 kDa indicating a homodimeric (α2) structure. Kinetic constants of the enzyme were determined at the optimal pH 7 and at 80°C. Rate dependence on both substrates followed Michaelis-Menten kinetics. The apparent Km values for glucose-6-phosphate and fructose-6-phosphate were 8.7 and 1.0 mM, respectively, and the corresponding apparentV max values were 800 and 130 U/mg. The enzyme had a temperature optimum of 96°C and showed a significant thermostability up to 100°C, which is in accordance with its physiological function under hyperthermophilic conditions. Based on the N-terminal amino acid sequence of the subunit, a single open reading frame (ORF; Pf_209264) was identified in the genome of P. furiosus. The ORF was characterized by functional overexpression in Escherichia coli as a gene, pgi, encoding glucose-6-phosphate isomerase. The recombinant PGI was purified and showed molecular and kinetic properties almost identical to those of the native PGI purified from P. furiosus. The deduced amino acid sequence of P. furiosus PGI did not reveal significant similarity to the conserved PGI superfamily of eubacteria and eucarya. This is the first description of an archaeal PGI, which represents a novel type of PGI.

Ultrastructure of Choriocarcinoma in Vitro

1969 ◽  
Vol 27 ◽  
pp. 362-363
Author(s):  
John C. Garancis ◽  
R. A. Pattillo
Keyword(s):  
Cell Line ◽  
Physiological Function ◽  
Cell System ◽  
Bewo Cell ◽  
Bewo Cells ◽  
Gestational Choriocarcinoma ◽  
Bewo Cell Line

Growth of cell system (BeWo-cell line) derived from human gestational choriocarcinoma has been established and continuously maintained in-vitro. Furthermore, it is evident from the previous studies that this cell line has retained the physiological function of the placental trophoblasts, namely the synthesis of human chorionic gonadotrophil(HCG).The BeWo cells were relatively small and possessed single nuclei, thus indicating that this cell line consists exclusively of cytotrophoblasts. In some instances cells appeared widely separated and their lateral surfaces were provided with numerous microvilli (Fig.1).

High resolution spot scan imaging of frozen, hydrated actin bundles with 400kV electrons

1992 ◽  
Vol 50 (1) ◽  
pp. 512-513
Author(s):  
J. Jakana ◽  
M.F. Schmid ◽  
P. Matsudaira ◽  
W. Chiu
Keyword(s):  
High Resolution ◽  
Binding Proteins ◽  
Actin Binding ◽  
Eukaryotic Cells ◽  
Dimensional Structure ◽  
Structural Basis ◽  
Actin Bundle ◽  
Actin Bundles ◽  
3 Dimensional ◽  
Macromolecular Assembly

Actin is a protein found in all eukaryotic cells. In its polymerized form, the cells use it for motility, cytokinesis and for cytoskeletal support. An example of this latter class is the actin bundle in the acrosomal process from the Limulus sperm. The different functions actin performs seem to arise from its interaction with the actin binding proteins. A 3-dimensional structure of this macromolecular assembly is essential to provide a structural basis for understanding this interaction in relationship to its development and functions.

Structure of clathrin cages and coats in ice

1986 ◽  
Vol 44 ◽  
pp. 94-97
Author(s):  
G.P.A. Vigers ◽  
R.A. Crowther ◽  
B.M.F. Pearse
Keyword(s):  
Electron Microscopy ◽  
Heavy Chain ◽  
Outer Part ◽  
Coated Vesicles ◽  
Eukaryotic Cells ◽  
Coat Proteins ◽  
Terminal Domain ◽  
Clathrin Heavy Chain ◽  
Membrane Components

Clathrin forms the polyhedral cage of coated vesicles, which mediate the transfer of selected membrane components within eukaryotic cells. Clathrin cages and coated vesicles have been extensively studied by electron microscopy of negatively stained preparations and shadowed specimens. From these studies the gross morphology of the outer part of the polyhedral coat has been established and some features of the packing of clathrin trimers into the coat have also been described. However these previous studies have not revealed any internal details about the position of the terminal domain of the clathrin heavy chain, the location of the 100kd-50kd accessory coat proteins or the interactions of the coat with the enclosed membrane.

The Hierarchic Order of Intermediate Filament Structure and Assembly

1985 ◽  
Vol 43 ◽  
pp. 722-725
Author(s):  
U. Aebi ◽  
E.C. Glavaris ◽  
R. Eichner
Keyword(s):  
Tissue Specificity ◽  
Structural Model ◽  
Eukaryotic Cells ◽  
Cdna Sequencing ◽  
Filament Structure ◽  
Keratin Filaments ◽  
Isoelectric Points ◽  
Immunological Crossreactivity

Five different classes of intermediate-sized filaments (IFs) have been identified in differentiated eukaryotic cells: vimentin in mesenchymal cells, desmin in muscle cells, neurofilaments in nerve cells, glial filaments in glial cells and keratin filaments in epithelial cells. Despite their tissue specificity, all IFs share several common attributes, including immunological crossreactivity, similar morphology (e.g. about 10 nm diameter - hence ‘10-nm filaments’) and the ability to reassemble in vitro from denatured subunits into filaments virtually indistinguishable from those observed in vivo. Further more, despite their proteinchemical heterogeneity (their MWs range from 40 kDa to 200 kDa and their isoelectric points from about 5 to 8), protein and cDNA sequencing of several IF polypeptides (for refs, see 1,2) have provided the framework for a common structural model of all IF subunits.

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