Direct targeting of cis-Golgi matrix proteins to the Golgi apparatus

2001 ◽  
Vol 114 (22) ◽  
pp. 4105-4115
Author(s):  
Shin-ichiro Yoshimura ◽  
Nobuhiro Nakamura ◽  
Francis A. Barr ◽  
Yoshio Misumi ◽  
Yukio Ikehara ◽  
...  
Keyword(s):  
Golgi Apparatus ◽  
Rat Kidney ◽  
Subcellular Fractionation ◽  
Golgi Membrane ◽  
Microsomal Membranes ◽  
Normal Rat ◽  
Direct Targeting ◽  
Golgi Matrix ◽  
Er Membrane

The targeting route of newly synthesized GM130 and GRASP65 to the Golgi apparatus was investigated by three different approaches. First, localization of pulse labeled GM130 and GRASP65 in normal rat kidney (NRK) cells was traced by subcellular fractionation followed by immunoprecipitation. Immediately after the pulse labeling, GM130 and GRASP65 were found in the Golgi but not in the endoplasmic reticulum (ER) membrane fractions, whereas a control Golgi membrane protein was still found in the ER membrane fractions. Second, epitope tagged GM130 and GRASP65 were expressed in NRK cells by plasmid microinjection into the nuclei and their localization was analyzed by immunofluorescence. When ER to Golgi transport was inhibited by prior microinjection of a GTP-restricted mutant of Sar1 protein into the cytosol, the expressed GM130 and GRASP65 showed clear Golgi localization. Last, binding of GM130 and GRASP65 to the membranes was analyzed in vitro. In vitro synthesized GM130 and GRASP65 specifically bound to purified Golgi membranes but not to microsomal membranes. The bound GM130 and GRASP65 were found to form a complex with pre-existing counterparts on the Golgi membrane. These results strongly suggested that GM130 and GRASP65 are directly targeted to the Golgi membrane without initial assembly on the ER and subsequent vesicular transport to the Golgi apparatus.

scholarly journals TheSaccharomyces cerevisiaePrenylcysteine Carboxyl Methyltransferase Ste14p Is in the Endoplasmic Reticulum Membrane

1998 ◽  
Vol 9 (8) ◽  
pp. 2231-2247 ◽  
Author(s):  
Julia D. Romano ◽  
Walter K. Schmidt ◽  
Susan Michaelis
Keyword(s):  
Endoplasmic Reticulum ◽  
Subcellular Fractionation ◽  
Endoplasmic Reticulum Membrane ◽  
Carboxyl Methylation ◽  
C Terminus ◽  
Eukaryotic Proteins ◽  
Internal Site ◽  
Membrane Spanning ◽  
Er Membrane

Eukaryotic proteins containing a C-terminal CAAX motif undergo a series of posttranslational CAAX-processing events that include isoprenylation, C-terminal proteolytic cleavage, and carboxyl methylation. We demonstrated previously that the STE14gene product of Saccharomyces cerevisiae mediates the carboxyl methylation step of CAAX processing in yeast. In this study, we have investigated the subcellular localization of Ste14p, a predicted membrane-spanning protein, using a polyclonal antibody generated against the C terminus of Ste14p and an in vitro methyltransferase assay. We demonstrate by immunofluorescence and subcellular fractionation that Ste14p and its associated activity are localized to the endoplasmic reticulum (ER) membrane of yeast. In addition, other studies from our laboratory have shown that the CAAX proteases are also ER membrane proteins. Together these results indicate that the intracellular site of CAAX protein processing is the ER membrane, presumably on its cytosolic face. Interestingly, the insertion of a hemagglutinin epitope tag at the N terminus, at the C terminus, or at an internal site disrupts the ER localization of Ste14p and results in its mislocalization, apparently to the Golgi. We have also expressed the Ste14p homologue from Schizosaccharomyces pombe, mam4p, in S. cerevisiae and have shown that mam4p complements a Δste14 mutant. This finding, plus additional recent examples of cross-species complementation, indicates that the CAAX methyltransferase family consists of functional homologues.

scholarly journals Assembly and disassembly of the Golgi complex: two processes arranged in a cis-trans direction.

1992 ◽  
Vol 116 (1) ◽  
pp. 69-83 ◽  
Author(s):  
J Alcalde ◽  
P Bonay ◽  
A Roa ◽  
S Vilaro ◽  
I V Sandoval
Keyword(s):  
Membrane Proteins ◽  
Golgi Complex ◽  
Rat Kidney ◽  
Brefeldin A ◽  
Golgi Membrane ◽  
Temperature Conditions ◽  
Selective Fusion ◽  
Normal Rat ◽  
Short Times

We have studied the disassembly and assembly of two morphologically and functionally distinct parts of the Golgi complex, the cis/middle and trans cisterna/trans network compartments. For this purpose we have followed the redistribution of three cis/middle- (GMPc-1, GMPc-2, MG 160) and two trans- (GMPt-1 and GMPt-2) Golgi membrane proteins during and after treatment of normal rat kidney (NRK) cells with brefeldin A (BFA). BFA induced complete disassembly of the cis/middle- and trans-Golgi complex and translocation of GMPc and GMPt to the ER. Cells treated for short times (3 min) with BFA showed extensive disorganization of both cis/middle- and trans-Golgi complexes. However, complete disorganization of the trans part required much longer incubations with the drug. Upon removal of BFA the Golgi complex was reassembled by a process consisting of three steps: (a) exist of cis/middle proteins from the ER and their accumulation into vesicular structures scattered throughout the cytoplasm; (b) gradual relocation and accumulation of the trans proteins in the vesicles containing the cis/middle proteins; and (c) assembly of the cisternae, and reconstruction of the Golgi complex within an area located in the vicinity of the centrosome from which the ER was excluded. Reconstruction of the cis/middle-Golgi complex occurred under temperature conditions inhibitory of the reorganization of the trans-Golgi complex, and was dependent on microtubules. Reconstruction of the trans-Golgi complex, disrupted with nocodazole after selective fusion of the cis/middle-Golgi complex with the ER, occurred after the release of cis/middle-Golgi proteins from the ER and the assembly of the cis/middle cisternae.

scholarly journals 3′-Untranslated regions of oxidative phosphorylation mRNAs function in vivo as enhancers of translation

2000 ◽  
Vol 352 (1) ◽  
pp. 109-115 ◽  
Author(s):  
Carlo M. Di LIEGRO ◽  
Marianna BELLAFIORE ◽  
José M. IZQUIERDO ◽  
Anja RANTANEN ◽  
José M. CUEZVA
Keyword(s):  
Oxidative Phosphorylation ◽  
Atp Synthase ◽  
Fluorescent Protein ◽  
Rat Kidney ◽  
In Vitro Translation ◽  
Mitochondrial Transcription Factor ◽  
Normal Rat ◽  
Green Fluorescent

Recent findings have indicated that the 3´-untranslated region (3´-UTR) of the mRNA encoding the β-catalytic subunit of the mitochondrial H+-ATP synthase has an in vitro translation-enhancing activity (TEA) [Izquierdo and Cuezva, Mol. Cell. Biol. (1997) 17, 5255–5268; Izquierdo and Cuezva, Biochem. J. (2000) 346, 849–855]. In the present work, we have expressed chimaeric plasmids that encode mRNA variants of green fluorescent protein in normal rat kidney and liver clone 9 cells to determine whether the 3´-UTRs of nuclear-encoded mRNAs involved in the biogenesis of mitochondria have an intrinsic TEA. TEA is found in the 3´-UTR of the mRNAs encoding the α- and β-subunits of the rat H+-ATP synthase complex, as well as in subunit IV of cytochrome c oxidase. No TEA is present in the 3´-UTR of the somatic mRNA encoding rat mitochondrial transcription factor A. Interestingly, the TEA of the 3´-UTR of mRNAs of oxidative phosphorylation is different, depending upon the cell type analysed. These data provide the first in vivo evidence of a novel cell-specific mechanism for the control of the translation of mRNAs required in mitochondrial function.

Insights into the Secretory Pathway, the Mechanism of Terminal Glycosylation and Intracellular Peptide Hormone Receptors from Studies on Hepatic Golgi Fractions

1981 ◽  
Vol 39 ◽  
pp. 516-519
Author(s):  
J.J.M. Bergeron ◽  
B.I. Posner ◽  
Jacques Paiement ◽  
R. Sikstrom ◽  
M. Khan
Keyword(s):  
Golgi Apparatus ◽  
Plasma Proteins ◽  
Secretory Pathway ◽  
Hormone Receptors ◽  
Peptide Hormone ◽  
Secretory Protein ◽  
Golgi Membrane ◽  
Membrane Structures

Recent studies on purified subcellular fractions of hepatic Golgi apparatus have provided insight into the functioning of the Golgi apparatus in vivo.The hepatocyte is the site of synthesis of most circulating plasma proteins. On a total protein basis, purified Golgi fractions revealed mainly secretory content (albumin, transferrin and other plasma proteins) as major constituents. After an in vivo injection of radiolabeled leucine, newly synthesized secretory protein followed a temporal route from cis to trans regions of Golgi apparatus before appearance in the plasma. This route was revealed by studies on disrupted Golgi fractions enriched in disparate regions of the Golgi apparatus.The terminal glycosylation of secretory glcyoproteins (e.g. transferrin) can be studied by observing the transfer of UDP-(3H)-galactose to endogenous acceptors within Golgi fractions. Transfer was shown to occur to a glycolipid (dolichyl galactosyl phosphate) probably on the cytosolic aspect of the Golgi membrane. Translocation of the labeled galactose across the membrane coincided with fusion of Golgi saccules in vitro. It is felt that during the process of Golgi membrane fusion, inverted lipid- micellar membrane structures translocate the dolichyl galactosyl phosphate from a cytosolic to a luminal orientation. Luminally oriented dolichyl galactosyl phosphate would then serve as substrate for galactose transfer to intraluminal glycopeptide acceptors via intraluminal galactosyl transferase enzyme.

Cytoplasmic hybrids, by fusing fish erythrophores and normal rat kidney cells

1991 ◽  
Vol 49 ◽  
pp. 266-267
Author(s):  
K.R. Porter ◽  
K.L. Anderson
Keyword(s):  
Rat Kidney ◽  
Structural Features ◽  
Cell Type ◽  
Pigment Granules ◽  
Normal Rat ◽  
Cytoplasmic Hybrids ◽  
Pigment Aggregation ◽  
General Architecture

When cultured together in the presence of PEG, these cells fuse (M1,M3) and survive in vitro for several days. This offers an opportunity to explore the capacity of one cell type (highly organized structurally) to impose it's structural features on a relatively unorganized cell type (NRK). Also, with two cells differing in several respects, one can ask questions regarding a role of the cell center in the control of pigment aggregation and dispersion, as well as the capacity of one cell type to assemble pigment granules in the cytplasm of another.First, in observations on general architecture .the hybrids have numerous microtubules (M3), but not the organized array of thousands observed in the erythrophores (M2). Furthermore, the microtubules in the hybrid are randomly oriented essentially as they are in the NRK cell (M4). There is a tendency observed in the hybrids for the pigment granules to concentrate among the microtubules and the cistemae of the ER (M3). Thus far, however, we have not succeeded consistently with epinephrine to induce aggregation, or with caffeine, dispersion.

scholarly journals Expression of a dominant allele of human ARF1 inhibits membrane traffic in vivo

1994 ◽  
Vol 124 (3) ◽  
pp. 289-300 ◽  
Author(s):  
CJ Zhang ◽  
AG Rosenwald ◽  
MC Willingham ◽  
S Skuntz ◽  
J Clark ◽  
...  
Keyword(s):  
Golgi Apparatus ◽  
Rat Kidney ◽  
Brefeldin A ◽  
Membrane Traffic ◽  
Immunoblot Analysis ◽  
In Vitro Assays ◽  
Wild Type ◽  
Discernible Effect

ADP-ribosylation factor (ARF) proteins and inhibitory peptides derived from ARFs have demonstrated activities in a number of in vitro assays that measure ER-to-Golgi and intra-Golgi transport and endosome fusion. To better understand the roles of ARF proteins in vivo, stable cell lines were obtained from normal rat kidney (NRK) cells transfected with either wild-type or a dominant activating allele ([Q71L]) of the human ARF1 gene under the control of the interferon-inducible mouse Mx1 promoter. Upon addition of interferon, expression of ARF1 proteins increased with a half-time of 7-8 h, as determined by immunoblot analysis. Induction of mutant ARF1, but not wild-type ARF1, led to an inhibition of protein secretion with kinetics similar to that observed for induction of protein expression. Examination of the Golgi apparatus and the ER by indirect immunofluorescence or transmission electron microscopy revealed that expression of low levels of mutant ARF1 protein correlated with a dramatic increase in vesiculation of the Golgi apparatus and expansion of the ER lumen, while expression of substantially higher levels of wild-type ARF1 had no discernible effect. Endocytosis was also inhibited by expression of mutant ARF1, but not by the wild-type protein. Finally, the expression of [Q71L]ARF1, but not wild-type ARF1, antagonized the actions of brefeldin A, as determined by the delayed loss of ARF and beta-COP from Golgi membranes and disruption of the Golgi apparatus. General models for the actions of ARF1 in membrane traffic events are discussed.

Glomerular handling of native albumin in the presence of circulating modified albumins by the normal rat kidney

2005 ◽  
Vol 289 (6) ◽  
pp. F1201-F1209 ◽  
Author(s):  
I. Londono ◽  
M. Bendayan
Keyword(s):  
Serum Albumin ◽  
Glomerular Filtration ◽  
Rat Kidney ◽  
Amino Acid Residues ◽  
Early Diabetes ◽  
Lysine Residues ◽  
Normal Rat ◽  
Endocytic Compartments ◽  
Modified Forms

Persistent hyperglycemia, as occurring in diabetes, induces changes in circulating as well as in structural proteins. These changes involve substitution of lysine residues by glucose adducts resulting in early Amadori products that evolve into toxic and active substances, the advanced glycation end adducts. In previous studies, we demonstrated that early glycated (Amadori) albumin infused into the circulation of normal animals induces transitory alterations of glomerular filtration. Attempting to elucidate the mechanisms underlying these changes, various molecular modifications were introduced in vitro to serum albumin. Glycation, acetylation, carboxymethylation, methylation, and succinylation, involving either a few or a significant number of amino acid residues, produced heavier and more anionic albumin molecules compared with the native one. Native and each of the modified albumin molecules were injected intravenously into normal rats, followed, 30 min later, by hapten-tagged native BSA. Changes in glomerular filtration were evaluated by morphometrical analysis of gold immunolabelings. Compared with native albumin, all the modified forms of albumin induced a deeper penetration of the tracer through the glomerular basement membrane revealing alterations in glomerular permselectivity. This was more evident for severely modified albumin molecules which displayed high labelings in the urinary space and endocytic compartments of proximal tubule epithelial cells. These results indicate that modifications of serum albumin, even minimal, as those occurring in early diabetes, could immediately affect the permselectivity properties of the glomerular wall leading, with time, to severe glomerulopathies.

scholarly journals COMPARISON OF REACTIONS OF ANTIBODIES TO RAT COLLAGEN AND TO RAT KIDNEY IN THE BASEMENT MEMBRANES OF RAT RENAL GLOMERULI

1969 ◽  
Vol 129 (6) ◽  
pp. 1145-1161 ◽  
Author(s):  
Sidney Rothbard ◽  
Robert F. Watson
Keyword(s):  
Rat Kidney ◽  
Basement Membranes ◽  
Heterologous Antigen ◽  
In Vitro Methods ◽  
Homologous Antigen ◽  
Normal Rat ◽  
Immunofluorescence Antibody ◽  
Glomerular Capillaries

By in vivo and in vitro methods of immunofluorescence, antibody to rat collagen and to rat kidney show the same regular, linear fluorescence following the outlines of the renal glomerular capillaries. Absorption of each antiserum with its homologous antigen completely removed the antibody for immunofluorescence, while absorption with the heterologous antigen had no effect. The nephrotoxicity persisted in the anti-kidney serum absorbed with collagen. By pretreatment of frozen normal rat kidney sections with various enzymes followed by immunofluorescence, it was shown that trypsin and hyaluronidase had no effect on the subsequent fluorescence of either antibody; papain reduced the fluorescence; and pepsin and Pronase acted on both antigens so that no fluorescence was present. One preparation of neuraminidase, derived from V. cholerae, reduced fluorescence of both antibodies in some preparations, but the same enzyme derived from influenza virus or C. perfringens had no effect on either. Collagenase completely prevented fluorescence of the antibody to collagen and had no effect on that to rat kidney. The findings in this study show that the antibody to collagen is directed to collagen in rat renal glomerular basement membranes and that the antibody to rat kidney reacts with some antigen other than collagen in these membranes.

The preliminary characterization of mitogens secreted by embryonic chick wing bud tissues in vitro

Development ◽  
1986 ◽  
Vol 93 (1) ◽  
pp. 257-265
Author(s):  
K. M. Bell
Keyword(s):  
Growth Factors ◽  
Limb Development ◽  
Rat Kidney ◽  
Active Regions ◽  
Limb Bud ◽  
Embryonic Chick ◽  
Bovine Endothelial Cells ◽  
Normal Rat ◽  
Wing Bud

Embryonic chick wing bud tissues secrete diffusible mitogens when cultured in vitro (Bell & McLachlan, 1985). These molecules may play an important role in limb development since media conditioned by morphogenetically active regions of the wing bud possess greater mitogenic activity than media conditioned by non-morphogenetic regions. These studies show that while the chick-derived growth factors were mitogenic for mouse-derived NIH 3T3,10T1/2 and NR6 cells and chick limb bud cells, they did not stimulate DNA synthesis in 3B11, PC13 END, normal rat kidney or bovine endothelial cells. Furthermore, the effects of the chick-derived mitogens were synergistically enhanced by insulin and PGF2α but remained unaffected by ECDGF, EGF, FGF and MSA. These findings indicate that embryonic chick limb bud cells synthesize and secrete growth factors which resemble in function other well-characterized growth factors and in particular PDGF.

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