scholarly journals Characterization of AtSEC12 and AtSAR1 (Proteins Likely Involved in Endoplasmic Reticulum and Golgi Transport)

1997 ◽  
Vol 114 (1) ◽  
pp. 315-324 ◽  
Author(s):  
M. Bar-Peled ◽  
N. V. Raikhel
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Transport

A characterization of heam uptake and intracellular distribution by isolated hepatocytes

1985 ◽  
Vol 5 (7) ◽  
pp. 609-614 ◽  
Author(s):  
A. Lodola
Keyword(s):  
Endoplasmic Reticulum ◽  
Specific Binding ◽  
Isolated Hepatocytes ◽  
Intracellular Distribution ◽  
Distribution Data ◽  
Temperature Dependent ◽  
Rat Hepatocyte ◽  
Isolated Rat ◽  
Endoplasmic Reticulum Fraction

The uptake and intracellular distribution of haem by isolated rat hepatocyte suspensions was studied. An increase in cell haem content occurred after a challenge with 5, 10 or 20 μM haem, supplied as methaemalbumin. The rate of haem uptake was temperature dependent; no non-specific binding occurred. Intracellular haem distribution data are consistent with a rapid association of haem with the endoplasmic reticulum fraction prior to its accumulation in the cytosol and at the mitochondrion.

The yeast SLY gene products, suppressors of defects in the essential GTP-binding Ypt1 protein, may act in endoplasmic reticulum-to-Golgi transport

1991 ◽  
Vol 11 (6) ◽  
pp. 2980-2993
Author(s):  
R Ossig ◽  
C Dascher ◽  
H H Trepte ◽  
H D Schmitt ◽  
D Gallwitz
Keyword(s):  
Endoplasmic Reticulum ◽  
Secretory Pathway ◽  
Protein Transport ◽  
Single Copy ◽  
Integral Membrane Protein ◽  
Carboxypeptidase Y ◽  
Null Mutant ◽  
Yeast Saccharomyces Cerevisiae ◽  
Golgi Transport ◽  
Gtp Binding

It has been shown previously that defects in the essential GTP-binding protein, Ypt1p, lead to a block in protein transport from the endoplasmic reticulum (ER) to the Golgi apparatus in the yeast Saccharomyces cerevisiae. Here we report that four newly discovered suppressors of YPT1 deletion (SLY1-20, SLY2, SLY12, and SLY41) to a varying degree restore ER-to-Golgi transport defects in cells lacking Ypt1p. These suppressors also partially complement the sec21-1 and sec22-3 mutants which lead to a defect early in the secretory pathway. Sly1p-depleted cells, as well as a conditional lethal sly2 null mutant at nonpermissive temperatures, accumulate ER membranes and core-glycosylated invertase and carboxypeptidase Y. The sly2 null mutant under restrictive conditions (37 degrees C) can be rescued by the multicopy suppressor SLY12 and the single-copy suppressor SLY1-20, indicating that these three SLY genes functionally interact. Sly2p is shown to be an integral membrane protein.

Cloning and characterization of sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) from crayfish axial muscle. Sarco/Endoplasmic Reticulum Ca(2+)-ATPase

2000 ◽  
Vol 203 (22) ◽  
pp. 3411-3423 ◽  
Author(s):  
Z. Zhang ◽  
D. Chen ◽  
M.G. Wheatly
Keyword(s):  
Endoplasmic Reticulum ◽  
Amino Acid ◽  
Procambarus Clarkii ◽  
Muscle Growth ◽  
Abdominal Muscle ◽  
Northern Analysis ◽  
Specific Expression ◽  
Loop Region ◽  
Moulting Cycle

The discontinuous pattern of muscle growth during the moulting cycle of a freshwater crustacean (the crayfish Procambarus clarkii) was used as a model system to examine the regulation of the expression of Sarco/Endoplasmic Reticulum Ca(2+)-ATPase (SERCA). We describe the cloning, sequencing and characterization of a novel SERCA cDNA (3856 bp) obtained from crayfish axial abdominal muscle by reverse transcription/polymerase chain reaction (RT-PCR) followed by rapid amplification of cDNA ends (RACE). This complete sequence contains a 145 base pair (bp) noncoding region at the 5′ end, a 3006 bp open reading frame coding for 1002 amino acid residues with a molecular mass of 110 kDa and 705 bp of untranslated region at the 3′ end. This enzyme contains all the conserved domains found in ‘P’-type ATPases, and the hydropathy profile suggests a transmembrane organization typical of other SERCAs. It exhibits 80% amino acid identity with Drosophila melanogaster SERCA, 79% identity with Artemia franciscana SERCA, 72% identity with rabbit fast-twitch muscle neonatal isoform SERCA1b, 71% identity with slow-twitch muscle isoform SERCA2 and 67% identity with SERCA3. Sequence alignment revealed that regions anchoring the cytoplasmic domain in the membrane were highly conserved and that most differences were in the NH(2) terminus, the central loop region and the COOH terminus. Northern analysis of total RNA from crayfish tissues probed with the 460 bp fragment initially isolated showed four bands (7.6, 7.0, 5.8 and 4.5 kilobases) displaying tissue-specific expression. SERCA was most abundant in muscle (axial abdominal, cardiac and stomach), where it is involved in Ca(2+) resequestration during relaxation, and in eggs, where it may be implicated in early embryogenesis. The level of SERCA mRNA expression in axial abdominal muscle varied during the moulting cycle as determined by slot-blot analysis. SERCA expression was greatest during intermoult and decreased to approximately 50% of this level during pre- and postmoult. Patterns of gene expression for SERCA and other sarcomeric proteins during the crustacean moulting cycle may be regulated by ecdysteroids and/or mechanical stimulation.

scholarly journals Comparative biosynthesis, covalent post-translational modifications and efficiency of prosegment cleavage of the prohormone convertases PC1 and PC2: glycosylation, sulphation and identification of the intracellular site of prosegment cleavage of PC1 and PC2

1993 ◽  
Vol 294 (3) ◽  
pp. 735-743 ◽  
Author(s):  
S Benjannet ◽  
N Rondeau ◽  
L Paquet ◽  
A Boudreault ◽  
C Lazure ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Brefeldin A ◽  
Pulse Labelling ◽  
Prohormone Convertases ◽  
Post Translational Modifications ◽  
Intracellular Degradation ◽  
Golgi Compartment ◽  
Carbonyl Cyanide ◽  
Insulinoma Cells

We present herein the pulse-chase analysis of the biosynthesis of the prohormone convertases PC1 and PC2 in the endocrine GH4C1 cells infected with vaccinia virus recombinants expressing these convertases. Characterization of the pulse-labelled enzymes demonstrated that pro-PC1 (88 kDa) is cleaved into PC1 (83 kDa) and pro-PC2 (75 kDa) into PC2 (68 kDa). Secretion of glycosylated and sulphated PC1 (84 kDa) occurs about 30 min after the onset of biosynthesis, whereas glycosylated and sulphated PC2 (68 kDa) is detected in the medium after between 1 and 2 h. Furthermore, in the case of pro-PC2 only, we observed that a fraction of this precursor escapes glycosylation. A small proportion (about 5%) of the intracellular glycosylated pro-PC2 (75 kDa) is sulphated, and it is this glycosylated and sulphated precursor that is cleaved into the secretable 68 kDa form of PC2. Major differences in the carbohydrate structures of PC1 and PC2 are demonstrated by the resistance of the secreted PC1 to endoglycosidase H digestion and sensitivity of the secreted PC2 to this enzyme. Inhibition of N-glycosylation with tunicamycin caused a dramatic intracellular degradation of these convertases within the endoplasmic reticulum, with the net effect of a reduction in the available activity of PC1 and PC2. These results emphasize the importance of N-glycosylation in the folding and stability of PC1 and PC2. Pulse-labelling experiments in uninfected mouse beta TC3 and rat Rin m5F insulinoma cells, which endogenously synthesize PC2, showed that, as in infected GH4C1 cells, pro-PC2 predominates intracellularly. In order to define the site of prosegment cleavage, pulse-chase analysis was performed at low temperature (15 degrees C) or after treatment of GH4C1 cells with either brefeldin A or carbonyl cyanide m-chlorophenylhydrazone. These results demonstrated that the onset of the conversions of pro-PC1 into PC1 and non-glycosylated pro-PC2 into PC2 (65 kDa) occur in a pre-Golgi compartment, presumably within the endoplasmic reticulum. In contrast, pulse labelling in the presence of Na(2)35SO4 demonstrated that the processing of glycosylated and sulphated pro-PC2 occurs within the Golgi apparatus. In order to test the possibility that zymogen processing is performed by furin, we co-expressed this convertase with either pro-PC1 or pro-PC2. The data demonstrated the inability of furin to cleave either proenzyme.

scholarly journals Cloning and Characterization of a Mouse Endoplasmic Reticulum Alkaline Ceramidase

2003 ◽  
Vol 278 (33) ◽  
pp. 31184-31191 ◽  
Author(s):  
Cungui Mao ◽  
Ruijuan Xu ◽  
Zdzislaw M. Szulc ◽  
Jacek Bielawski ◽  
Kevin P. Becker ◽  
...  
Keyword(s):  
Endoplasmic Reticulum
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