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At least 685 records · Page 38Linked to original sources
PubMed1996

Golgi apparatus mammary gland casein kinase: monitoring by a specific peptide substrate and definition of specificity determinants.

The casein kinase from the Golgi apparatus of lactating mammary gland (GEF-CK) is distinct from ubiquitous 'casein kinases' termed protein kinases CK1 and CK2 and appears to define a family of secretory pathways protein kinases that phosphorylate seryl residues followed by an acidic residue at position +2. In this report we show that a new synthetic peptide substrate derived from beta-casein (beta[28-40]) is suitable for the fast, efficient and selective monitoring of GEF-CK, being unaffected by CK1 and CK2, and we define the consensus sequence of this protein kinase as being Ser-Xaa-Glu/SerP, distinct from that of CK2 (Ser/Thr-X-X-Glu/Asp/SerP/TyrP). In particular, the failure to recognize Asp as crucial specificity determinant prevents the phosphorylation of the specific CK2 peptide substrate RRRADDSDDDDD by GEF-CK. Thus, peptide substrates are now available for the fast and specific monitoring of all the three classes of 'casein kinases', CK1, CK2 and GEF-CK.

Amino Acid Sequence↗
PubMed2000

Fragmentation of the Golgi apparatus of the anterior horn cells in patients with familial amyotrophic lateral sclerosis with SOD1 mutations and posterior column involvement.

The Golgi apparatus (GA) of the anterior horn cells in the spinal cord was examined by immunohistological methods with an antibody against the MG-160 protein, a conserved intrinsic membrane sialoglycoprotein of the medial cisternae of the GA, in three patients with familial amyotrophic lateral sclerosis (FALS) with posterior column involvement. Large motor neurons in the anterior horns were markedly reduced in number and 10 of total 14 remaining large motor neurons showed fragmentation and a reduction in the number of the elements of the GA. The fragmentation of the GA was identical to that previously reported in motor neurons of the spinal cord and motor cortex from patients with sporadic ALS and in transgenic mice expressing the G93A mutation of the gene encoding the Cu/Zn superoxide dismutase months before the onset of paralysis. This is the first report of fragmented GA of the anterior horn cells in patients with FALS with posterior column involvement. The findings suggest that the GA is a common target in the neuronal degeneration in sporadic and FALS.

Amino Acid Substitution↗
PubMed1996

Expression of the cholera toxin B subunit in the Golgi apparatus of Swiss 3T3 cells inhibits DNA synthesis induced by basic fibroblast growth factor.

We attempted to express the cholera toxin B subunit (CTXB) in the Golgi apparatus of cultured mammalian cells by means of gene transfection. Complementary DNA of CTXB was ligated with the Golgi-retention signal sequence of human beta 1,4 galactosyltransferase cDNA, and the chimeric gene yielded was inserted into a mammalian expression vector. The resultant construct was transfected into COS-1 cells for transient expression and into Swiss 3T3 cells for stable expression. The expression of a fusion protein encoded by the chimeric gene was demonstrated according to the following criteria: first, detection of a protein exhibiting the expected molecular mass on Western blot analysis using an anti-CTXB antibody; second, detection of the protein located in the Golgi area by indirect immunofluoresence microscopy; and third, detection of GM1 binding activity in cell lysates. Stable transformants satisfying the above criteria were subjected to an assay for mitogen-induced DNA synthesis. These transformants exhibited significantly lower DNA synthesis than mock transfection cells on stimulation with basic fibroblast growth factor (bFGF), whereas the two types of cells exhibited similar responses to 10% fetal calf serum and other mitogens, such as epidermal growth factor, 12-O-tetradecanoylphorbol-13-acetate, calcium ionophore A23187, and platelet-derived growth factor. Analysis of the binding of radio-iodinated bFGF to the cells revealed that the transformants did not exhibit a significant decrease in the binding affinity or the number of high affinity sites. These results suggest that the fusion protein specifically inhibits the bFGF signaling not at the binding step but rather at a later step(s) triggered by the binding.

3T3 Cells↗
PubMed1987

The Golgi apparatus in the acinar cells of the developing embryonic pancreas: II. Localization of lectin-binding sites.

The reaction patterns of the Golgi apparatus following staining with the lectins concanavalin A (ConA), Ricinus communis I agglutinin (RCA I), and Helix pomatia lectin (HPA) were studied in the pancreas acinar cells of rat embryos in the course of cell differentiation from day 13 through day 20 of gestation. The binding reactions were localized by means of pre-embedment incubation of 10-microns-thick cryosections of pancreas tissue, prefixed in a mixture of 4% formaldehyde/0.5% glutaraldehyde, using horseradish peroxidase for electron microscope visualization. ConA, which preferentially binds to alpha-D-mannosyl residues, consistently stained the cisternae of the cis Golgi side. The majority of the stacks also showed ConA staining of medial cisternae. The reaction of the trans side was variable; in each stage of development, the cisternae of the trans Golgi side either were devoid of labeling or appeared intensely stained. The reactions obtained with RCA I, which recognizes terminal beta-D-galactosyl residues, changed in the course of cell differentiation; in the protodifferentiated and early differentiated states, the system of "rigid lamellae," located at the trans side of the Golgi stacks, was intensely labeled, but became unreactive after production of secretion granules had started, the reaction then being restricted to the stacked saccules. In regard to the Golgi stacks in each of the developmental stages, RCA I binding sites either were confined to the trans cisternae, or, in addition, were found distributed across elements of the medial and cis compartments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

[A morphofunctional analysis of the changes in the Golgi apparatus in the epitheliocytes of the frog bladder under conditions of the vasopressin stimulation of water transport].

Structural and chemical peculiarities of the Golgi apparatus elements in granular cells of the normal frog urinary epithelium and under vasopressin stimulation of water transport have been studied with different electron microscopic methods: standard chemical fixation, prolonged osmification, freeze-substitution, freeze-fracture, immunocytochemistry, and electron-probe X-ray microanalysis. The structure of the main Golgi elements and its derivatives in normal cells and under the stimulation of water transport has been described. The association of microtubules with the Golgi cisternae was shown. Microtubules are supposed to participate in the support of integrity of the Golgi complex (in normal cells). Under stimulated water transport, depolymerization of microtubules seems to occur, resulting eventually in the Golgi fragmentation. Participation of some specific granules, that are the Golgi derivatives, in the increase of apical membrane water permeability has been shown as the insertion of water channels. Besides, under big water flows, the Golgi cis-cisternae were shown to participate in the formation of large vacuoles containing low potassium. A supposition is put forward that these vacuoles may perform an osmoregulative function in the cell, similar to that of contractile vacuoles of Protozoa.

Animals↗
PubMed1986

Cytoprotective effect of 16,16' dimethyl prostaglandin E2 (dm PGE2) on streptozotocin-induced biochemical alterations of Golgi-rich membrane fraction in comparison with morphology of rat liver Golgi apparatus in situ.

In 10-11 days after single, intraperitoneal injection of streptozotocin we found a lower (although not statistically significant) yield of Golgi-rich membrane fraction in comparison with control. In these rats similar to control specific activity of galactosyltransferase in nM Gal transferred per h and mg of protein, and statistically significant lower total activity of this enzyme expressed in nM Gal transferred per h and per total liver (t = 2.9666, 0.01 less than p less than 0.05) were found. Organization of Golgi apparatus in situ showed alterations that indicated suppression of secretory activity. Within the dm PGE2 protected animal group the obtained data equal control data.

16,16-Dimethylprostaglandin E2↗
PubMed2006

Calcium in the Golgi apparatus.

The secretory-pathway Ca2+-ATPases (SPCAs) represent a recently recognized family of phosphorylation-type ATPases that supply the lumen of the Golgi apparatus with Ca2+ and Mn2+ needed for the normal functioning of this structure. Mutations of the human SPCA1 gene (ATP2C1) cause Hailey-Hailey disease, an autosomal dominant skin disorder in which keratinocytes in the suprabasal layer of the epidermis detach. We will first review the physiology of the SPCAs and then discuss how mutated SPCA1 proteins can lead to an epidermal disorder.

Animals↗
PubMed2000

The transmembrane protein p23 contributes to the organization of the Golgi apparatus.

In previous studies we have shown that p23, a member of the p24-family of small transmembrane proteins, is highly abundant in membranes of the cis-Golgi network (CGN), and is involved in sorting/trafficking in the early secretory pathway. In the present study, we have further investigated the role of p23 after ectopic expression. We found that ectopically expressed p23 folded and oligomerized properly, even after overexpression. However, in contrast to endogenous p23, exogenous p23 molecules did not localize to the CGN, but induced a significant expansion of characteristic smooth ER membranes, where they accumulated in high amounts. This ER-derived, p23-rich subdomain displayed a highly regular morphology, consisting of tubules and/or cisternae of constant diameter, which were reminiscent of the CGN membranes containing p23 in control cells. The expression of exogenous p23 also led to the specific relocalization of endogenous p23, but not of other proteins, to these specialized ER-derived membranes. Relocalization of p23 modified the ultrastructure of the CGN and Golgi membranes, but did not affect anterograde and retrograde transport reactions to any significant extent. We conclude (i) that p23 has a morphogenic activity that contributes to the morphology of CGN-membranes; and (ii) that the presence of p23 in the CGN is necessary for the proper organization of the Golgi apparatus.

Golgi Apparatus↗
PubMed1993

Effect of shear stress upon localization of the Golgi apparatus and microtubule organizing center in isolated cultured endothelial cells.

Despite substantial evidence to suggest that directed cell migration is dependent upon positioning of the Golgi apparatus (GA) and the microtubule organizing center (MTOC), some controversy exists about whether such a relationship is relevant to endothelial cells under flow. The present study was undertaken to provide an indepth investigation of the relationship between shear stress, GA/MTOC localization, cell migration and nuclear position. Bovine carotid endothelial cells were exposed to 22 or 88 dynes/cm2 for 0.5, 2, 8 or 24 h, and localization of their GA/MTOCs was determined relative to the direction of flow. In no-flow control specimens, (0, 0.5, 2, 8 and 24 h) there was no change in the equally distributed GA/MTOCs. In contrast, during the first 8 h at 88 dynes/cm2 and by 2 h at 22 dynes/cm2 there was a significant increase in the number of cells with GA/MTOCs localized upstream to flow direction. The effect was temporary, however, and by 24 h there was no significant difference between the no-flow, 22 and 88 dynes/cm2 specimens. Analysis of GA/MTOC localization with respect to the direction of cell migration determined that 72.5% of no-flow cells possessed GA/MTOCs localized to the sides of nuclei nearest the direction of migration. In contrast, 64% of the specimens shear stressed over the same time period had GA/MTOCs localized to the sides of nuclei opposite the direction of migration. These results suggest that positioning of the GA/MTOC in endothelial cells is not dependent completely upon the direction of migration.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2004

Disruption of the structure of the Golgi apparatus and the function of the secretory pathway by mutants G93A and G85R of Cu, Zn superoxide dismutase (SOD1) of familial amyotrophic lateral sclerosis.

The Golgi apparatus of motor neurons (GA) is fragmented in sporadic amyotrophic lateral sclerosis (ALS), in familial ALS with SOD1 mutations, and in mice that express SOD1G93A of familial ALS, in which it was detected months before paralysis. In paralyzed transgenic mice expressing SOD1G93A or SOD1G85R, mutant proteins aggregated not only in the cytoplasm of motor neurons, but also in astrocytes and oligodendrocytes. Furthermore, aggregation of the G85R protein damaged astrocytes and was associated with rapidly progressing disease. In order to gain insight into the functional state of the fragmented GA, we examined the effects of S0D1 mutants G93A and G85R in Chinese Hamster Ovary Cells (CHO). In contrast to cells expressing the wt and G93A, the G85R expressers had no SOD1 activity. However, cells expressing both mutants, and to a lesser degree the wt, showed decreased survival, fragmentation of the GA, and dysfunction of the secretory pathway, which was assessed by measuring the amount of cell surface co-expressed CD4, a glycoprotein processed through the GA. The G93A and wt proteins were partially recovered in detergent insoluble fractions; while the recovery of G85R was minimal. Both mutants showed equal reductions of cell survival and function of the secretory pathway, in comparison to the wt and cells expressing mutant alsin, a protein found in rare cases of fALS. These results are consistent with the conclusion that the two SOD1 mutants, by an unknown mechanism, promote the dispersion of the GA and the dysfunction of the secretory pathway. This and other in vitro models of mutant SOD1 toxicity may prove useful in the elucidation of pathogenetic mechanisms.

Amyotrophic Lateral Sclerosis↗
PubMed2000

The neuronal Golgi apparatus is fragmented in transgenic mice expressing a mutant human SOD1, but not in mice expressing the human NF-H gene.

Fragmentation of the Golgi apparatus (GA) of motor neurons was first described in sporadic amyotrophic lateral sclerosis (ALS) and later confirmed in transgenic mice expressing the G93A mutation of the gene encoding the enzyme Cu,Zn superoxide dismutase (SOD1(G93A)) found in some cases of familial ALS. In these transgenic mice, however, the fragmentation of the neuronal GA was associated with cytoplasmic and mitochondrial vacuoles not seen in ALS. The present new series of transgenic mice expressing 14-17 trans gene copies of SOD1(G93A), compared to 25 copies in the mice we studied previously, showed consistent fragmentation of the GA of spinal cord motor neurons, axonal swellings, Lewy-like body inclusions in neurons and glia, but none of the cytoplasmic or mitochondrial vacuoles originally reported. Thus, this animal model recapitulates the clinical and most neuropathological findings of sporadic ALS. Neurofilaments (NF) accumulate in axons and, less often, in neuronal perikarya in most cases of sporadic ALS and they have been implicated in its pathogenesis. In order to investigate whether fragmentation of the neuronal GA also occurs in association with accumulation of perikaryal NFs, we studied the organelle in transgenic mice expressing the heavy subunit of human neurofilaments (NF-H) which developed a motor neuronopathy resembling ALS. The neuronal GA of mice expressing NF-H, however, was intact despite massive accumulation of NFs in both perikarya and axons of motor neurons. In contrast, in transgenic mice expressing SOD1(G93A), the GA was fragmented despite the absence of accumulation of perikaryal NFs. These findings suggest that, in transgenic mice with neuronopathies caused by the expression of mutant SOD1(G93A) or the human NF-H, the GA and the perikaryal NFs are independently involved in the pathogenesis. The evidence suggests that the GA plays a central role in the pathogenesis of the vast majority of sporadic ALS and in FALS with SOD1 mutations.

Amyotrophic Lateral Sclerosis↗
PubMed2001

Rer1p, a retrieval receptor for endoplasmic reticulum membrane proteins, is dynamically localized to the Golgi apparatus by coatomer.

Rer1p, a yeast Golgi membrane protein, is required for the retrieval of a set of endoplasmic reticulum (ER) membrane proteins. We present the first evidence that Rer1p directly interacts with the transmembrane domain (TMD) of Sec12p which contains a retrieval signal. A green fluorescent protein (GFP) fusion of Rer1p rapidly cycles between the Golgi and the ER. Either a lesion of coatomer or deletion of the COOH-terminal tail of Rer1p causes its mislocalization to the vacuole. The COOH-terminal Rer1p tail interacts in vitro with a coatomer complex containing alpha and gamma subunits. These findings not only give the proof that Rer1p is a novel type of retrieval receptor recognizing the TMD in the Golgi but also indicate that coatomer actively regulates the function and localization of Rer1p.

Amino Acid Motifs↗
PubMedDate not supplied

[The role of vitamin A in the functioning of Golgi apparatus].

Vitamin A participation in the Golgi complex functioning has been studied using the mucosa intermediate area of the chicken glandular stomach as a model. It is shown that in case of A-avitaminosis the electrophoretic profile of soluble proteins of mucosa and [I-14C]acetate and Na2(35)SO4 incorporation into it do not change, while in a secretion all these parameters are highly changed. Four glycoproteins are isolated from the mucous secretion, they differ in solubility in 6% perchloric acid and in staining by kumassi and alcine blue. These data and those obtained before underlie the conclusion that the effect of vitamin A on the secretion formation is realized on the level of the Golgi complex function.

Animals↗
PubMed1993

Membrane protein retention in the yeast Golgi apparatus: dipeptidyl aminopeptidase A is retained by a cytoplasmic signal containing aromatic residues.

The mechanism by which yeast dipeptidyl aminopeptidase (DPAP) A, type II integral membrane protein, is retained in the late Golgi apparatus has been investigated. Prior work demonstrated that the 118-amino acid cytoplasmic domain is both necessary and sufficient for Golgi retention and that mutant or overexpressed DPAP A no longer retained in the Golgi was delivered directly to the vacuolar membrane (Roberts, C. J., S. F. Nothwehr, and T. H. Stevens. 1992. J. Cell Biol. 119:69-83). Replacement of the DPAP A transmembrane domain with a synthetic hydrophobic sequence did not affect either Golgi retention of DPAP A or vacuolar delivery of the retention-defective form of DPAP A. These results indicate that the DPAP A transmembrane domain is not involved in either Golgi retention or targeting of this membrane protein. A detailed mutational analysis of the cytoplasmic domain of DPAP A indicated that the most important elements for retention were within the eight residue stretch 85-92. A 10-amino acid region from DPAP A (81-90) was sufficient for Golgi retention of alkaline phosphatase, a type II vacuolar membrane protein. Detailed mutational analysis within this 10-amino acid sufficient region demonstrated that a Phe-X-Phe-X-Asp motif was absolutely required for efficient retention. The efficiency of Golgi retention via the DPAP A signal could be diminished by overexpression of wild type but not retention-defective versions of Kex2p, another late Golgi membrane protein, suggesting that multiple Golgi membrane proteins may be retained by a common machinery. These results imply a role for a cytoplasmic signal involving aromatic residues in retention of late Golgi membrane proteins in the yeast Saccharomyces cerevisiae.

Amino Acid Sequence↗
PubMed2005

Golgins and GTPases, giving identity and structure to the Golgi apparatus.

In this review we will focus on the recent advances in how coiled-coil proteins of the golgin family give identity and structure to the Golgi apparatus in animal cells. A number of recent studies reveal a common theme for the targeting of golgins containing the ARL-binding GRIP domain, and the related ARF-binding GRAB domain. Similarly, other golgins such as the vesicle tethering factor p115 and Bicaudal-D are targeted by the Rab GTPases, Rab1 and Rab6, respectively. Together golgins and their regulatory GTPases form a complex network, commonly known as the Golgi matrix, which organizes Golgi membranes and regulates membrane trafficking.

Animals↗
PubMed2000

GRP94 (endoplasmin) co-purifies with and is phosphorylated by Golgi apparatus casein kinase.

A phosphorylatable protein band of about 94 kDa (as judged by SDS-PAGE) which co-purifies and co-immunoprecipitates with Golgi apparatus casein kinase (G-CK) from rat lactating mammary gland has been shown by mass spectrometric sequence analysis to be identical or very similar to the glucose-regulated protein, GRP94. GRP94 is also readily phosphorylated by G-CK (K(m)=0.2 microM) at seryl sites which are different from the sites affected by casein kinase-2 (CK2) in the same protein. A study with peptide substrates would indicate that the G-CK sites in GRP94 conform to the motif S-R/K-E-X (X being different from D and E) which is not recognized by CK2.

Amino Acid Motifs↗