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G Hinz

Publications and source records attributed to G Hinz.

At least 19 recordsLinked to original sources
PubMed2001

Vacuolar storage proteins are sorted in the cis-cisternae of the pea cotyledon Golgi apparatus.

Developing pea cotyledons contain functionally different vacuoles, a protein storage vacuole and a lytic vacuole. Lumenal as well as membrane proteins of the protein storage vacuole exit the Golgi apparatus in dense vesicles rather than in clathrin-coated vesicles (CCVs). Although the sorting receptor for vacuolar hydrolases BP-80 is present in CCVs, it is not detectable in dense vesicles. To localize these different vacuolar sorting events in the Golgi, we have compared the distribution of vacuolar storage proteins and of alpha-TIP, a membrane protein of the protein storage vacuole, with the distribution of the vacuolar sorting receptor BP-80 across the Golgi stack. Analysis of immunogold labeling from cryosections and from high pressure frozen samples has revealed a steep gradient in the distribution of the storage proteins within the Golgi stack. Intense labeling for storage proteins was registered for the cis-cisternae, contrasting with very low labeling for these antigens in the trans-cisternae. The distribution of BP-80 was the reverse, showing a peak in the trans-Golgi network with very low labeling of the cis-cisternae. These results indicate a spatial separation of different vacuolar sorting events in the Golgi apparatus of developing pea cotyledons.

COP-Coated Vesicles↗
PubMed1999

Localization of pyrophosphatase in membranes of cauliflower inflorescence cells.

Using a polyclonal antiserum specific for the tonoplastic H(+)-pyrophosphatase (tPPase), significant amounts of antigenic polypeptides of the correct molecular mass were detected in Western blots of plasma membrane isolated from cauliflower (Brassica oleracea L.) inflorescence by phase-partitioning and subsequent sucrose density centrifugation. Potassium iodide-stripped plasma membranes continued to give a strong positive signal, indicating that the PPase antigen detected was not a result of contamination through soluble PPase released during homogenisation. The same preparation contained negligible vacuolar (v)H(+)-ATPase activity and the A subunit of the vATPase could not be detected by immunoblotting. Plasma membrane fractions exhibited a proton-pumping activity with ATP as substrate, but such an activity was not measurable with pyrophosphate, although the hydrolysis of this substrate was recorded. By contrast, pyrophosphate supported proton pumping in tonoplast-containing fractions. Immunogold electron microscopy confirmed the presence of PPase at the plasma membrane as well as at the tonoplast, trans Golgi network, and multivesicular bodies. The density of immunogold label was higher at the plasma membrane than at the tonoplast, except for membrane fragments occurring in the lumen of the vacuoles which stained very conspicuously.

Animals↗
PubMed1999

Vacuolar storage proteins and the putative vacuolar sorting receptor BP-80 exit the golgi apparatus of developing pea cotyledons in different transport vesicles

In the parenchyma cells of developing legume cotyledons, storage proteins are deposited in a special type of vacuole, known as the protein storage vacuole (PSV). Storage proteins are synthesized at the endoplasmic reticulum and pass through the Golgi apparatus. In contrast to lysosomal acid hydrolases, storage proteins exit the Golgi apparatus in 130-nm-diameter electron-dense vesicles rather than in clathrin-coated vesicles. By combining isopycnic and rate zonal sucrose density gradient centrifugation with phase partitioning, we obtained a highly enriched dense vesicle fraction. This fraction contained prolegumin, which is the precursor of one of the major storage proteins. In dense vesicles, prolegumin occurred in a more aggregated form than it did in the endoplasmic reticulum. The putative vacuolar sorting receptor BP-80 was highly enriched in purified clathrin-coated vesicles, which, in turn, did not contain prolegumin. The amount of BP-80 was markedly reduced in the dense vesicle fraction. This result was confirmed by quantitative immunogold labeling of cryosections of pea cotyledons: whereas antibodies raised against BP-80 significantly labeled the Golgi stacks, labeling of the dense vesicles could not be detected. In contrast, 90% of the dense vesicles were labeled with antibodies raised against alpha-TIP (for tonoplast intrinsic protein), which is the aquaporin specific for the membrane of the PSV. These results lead to the conclusions that storage proteins and alpha-TIP are delivered via the same vesicular pathway into the PSVs and that the dense vesicles that carry these proteins in turn do not contain BP-80.

Journal Article↗
PubMed1998

Eosinophil cationic protein in sputum is dependent on temperature and time.

Eosinophil cationic protein (ECP) in sputum may be used to estimate the severity of bronchial inflammation and obstruction in asthmatics as well as to monitor asthma drug therapy. For this purpose, standardized processing of sputum is important. The aim of our study was to determine whether time and temperature influence the ECP concentration in the sputum of asthmatics. The samples of induced sputum obtained from 12 patients with stable asthma were homogenized using ultrasonification, and centrifuged. Supernatants were evenly divided and stored for 1, 6, 24 or 72 h at either 4 or 25 degrees C, then frozen at -80 degrees C. The ECP concentrations were determined using fluoroimmunoassay and compared with the immediately frozen samples. After storing at 4 degrees C, the ECP levels at the four time points were 101.2, 96.0, 98.2 and 90.6% of the initial concentration, respectively. When sputum specimens were stored at 25 degrees C, ECP levels decreased to 96.1, 94.4, 90.7 and 87.7%, respectively. The influence of time on ECP concentrations in sputa was statistically significant (p=0.02). A significant temperature effect was found when comparing the specimens stored at 4 degrees C with those at 25 degrees C (p=0.03). Looking at individual time points, a significant decrease in ECP concentration was only seen at 25 degrees C after 24 and 72 h. We conclude that eosinophilic cationic protein in the sputum of asthmatics decreases in a time- and temperature-dependent process. If sputa cannot be processed after obtaining the specimens, they should be stored in a refrigerator at 4 degrees C, until eosinophilic cationic protein is measured.

Adult↗
PubMed1998

The molecular characterization of transport vesicles.

Secretion, endocytosis and transport to the lytic compartment are fundamental, highly coordinated features of the eukaryotic cell. These intracellular transport processes are facilitated by vesicles, many of which are small (100 nm or less in diameter) and 'coated' on their cytoplasmic surface. Research into the structure of the coat proteins and how they interact with the components of the vesicle membrane to ensure the selective packaging of the cargo molecules and their correct targeting, has been quite extensive in mammalian and yeast cell biology. By contrast, our knowledge of the corresponding types of transport vesicles in plant cells is limited. Nevertheless, the available data indicate that a considerable homology between plant and non-plant coat polypeptides exists, and it is also suggestive of a certain similarity in the mechanisms underlying targeting in all eukaryotes. In this article we shall concentrate on three major types of transport vesicles: clathrin-coated vesicles, COP-coated vesicles, and 'dense' vesicles, the latter of which are responsible for the transport of vacuolar storage proteins in maturing legume cotyledons. For each we will summarize the current literature on animal and yeast cells, and then present the relevant data derived from work on plant cells. In addition, we briefly review the evidence in support of the 'SNARE' hypothesis, which explains how vesicles find and fuse with their target membrane.

Animals↗
PubMed1996

Transport of storage proteins to the vacuole is mediated by vesicles without a clathrin coat.

Storage parenchyma cells of developing legume cotyledons actively transport large amounts of storage proteins to protein storage vacuoles (PSV). These proteins are synthesized on the endoplasmic reticulum and pass through the Golgi apparatus. Clathrin coated vesicles (CCV) and small electron dense vesicles found near the trans-Golgi network (TGN) have both been implicated in the Golgi-to-vacuole transport step. Recent findings that protein storage cells contain more than one type of vacuole have necessitated a re-examination of the role of both types of vesicles in vacuolar protein transport. Immunoblots of highly purified CCV preparations and immunogold labelling with antibodies to the storage proteins vicilin and legumin, indicate that the dense vesicles, but not the CCV, are involved in storage protein transport in pea cotyledons. This result is supported by the finding that alpha-TIP, a protein characteristic of the PSV membrane, is absent from CCV. In addition, complex glycoproteins appear to be carried by CCV but are not detectable in the PSV. We suggest on the basis of these data that storage proteins and other vacuolar proteins such as acid hydrolases are not sorted by the same mechanism and are transported by different types of vesicles to different types of vacuoles.

Blotting, Western↗
PubMed1995

Protein storage vacuoles form de novo during pea cotyledon development.

We have investigated the formation of protein storage vacuoles in peas (Pisum sativum L.) in order to determine whether this organelle arises de novo during cotyledon development. A comparison of different stages in cotyledon development indicates that soluble protease activities decline and the amounts of storage proteins and the integral membrane protein of the protein body, alpha-TIP, increase during seed maturation. On linear sucrose density gradients we have been able to distinguish between two separate vesicle populations: one enriched in alpha-TIP, and one in TIP-Ma 27, a membrane protein characteristic of vegetative vacuoles. Both vesicle populations possess, however, PPase and V-ATPase activities. Conventionally fixed cotyledonary tissue at an intermediate stage in cotyledon development reveals the presence of a complex tubular-cisternal membrane system that seems to surround the pre-existing vacuoles. The latter gradually become compressed as a result of dilation of the former membrane system. This was confirmed immunocytochemically with the TIP-Ma 27 antiserum. Deposits of the storage proteins vicilin and legumin in the lumen, and the presence of alpha-TIP in the membranes of the expanding membrane system provide evidence of its identity as a precursor to the protein storage vacuole.

Adenosine Triphosphatases↗
PubMed1991

[The behavior of substance P concentration in rat plasma in the acute single- and combined-actions of trichloroethylene and ethanol].

In experimental studies in male Wistar-rats exerted for determination of trichloroethylene, ethanol and combined action influences on the substance P plasma concentrations. These concentrations were determined by a radioimmunological method. The acute exposure of trichloroethylene and ethanol lead to a significant rise of substance P. We found high substance P concentration peaks, in principle, 4 h after acute exposure and the combined action shows the greatest effect.

Animals↗
PubMed1988

Phosphorylation of a 51-kDa envelope membrane polypeptide involved in protein translocation into chloroplasts.

In this report we demonstrate that a 51-kDa outer-envelope membrane protein (P51) is involved in protein translocation into chloroplasts. Furthermore it is shown that phosphorylation of P51 is functionally related to the process of binding and/or importing precursor proteins into chloroplasts. Several lines of evidence have been obtained supporting this suggestion. First, protein import into chloroplasts was inhibited by the membrane-impermeable agent pyridoxal 5'-phosphate, which has been shown to react with a component of the protein-import apparatus. Phosphorylation of envelope membrane polypeptides using [gamma-32P]ATP in the presence of pyridoxal 5'-phosphate resulted in an increased incorporation of 32P radiolabel into a 51-kDa membrane polypeptide (P51). A close correlation between the inhibition of protein import and the increase in the phosphorylation state of P51, both as a function of PLP concentration, was observed. Second, binding of purified precursor proteins to chloroplasts resulted in a specific increase in the phosphorylation state of P51. This effect was not exerted by the mature form of the precursor protein lacking the presequence. Third, internally generated ATP was able to compete specifically with externally added [gamma-32P]ATP for the phosphorylation of P51. Fourth, digestion of the outer-envelope membrane with low amounts of thermolysin resulted in a loss of protein import activity, which was associated with the removal of the phosphorylation site of P51. Phosphorylation of P51 proceeds with an apparent Km (ATP) of about 5 microM, which is much lower than the ATP concentration required for the protein translocation itself. We suggest that two different ATP-dependent processes are involved in protein translocation into chloroplasts. P51 represent presumably a regulatory component of the protein-import apparatus or the protein receptor itself.

Adenosine Triphosphate↗
PubMed1988

[EEG changes in rats after subchronic exposure to ethanol].

EEG-investigations in rats were carried out 2 weeks after finishing a 3-month exposure scheme to ethanol (113 mmol/kg b.w., p.o., 5 times per week). We found pronounced disturbances of the sleep-wake behaviour as a reflection of a serious damage of the alertness-regulating system. The previously exposed animals did show disturbed vigilance and changes in the course and character of sleep, a reduction of power density in the alpha-, and an increase within the beta- and delta frequency bands of the EEG. The essential conclusions drawn from the experiment are comparable with EEG-changes in abstinent alcoholics, as reported in the literature.

Animals↗
PubMed1987

[Changes in substance P concentration in rat plasma under different conditions of blood letting].

The influence of various conditions at blood-letting on the concentration of SP in the plasma was investigated in male Wistar rats as background for following studies on effects of noxae. Narcotic substance (hexobarbital, ether), CO2-suffocation and the mechanical kinds of killing (cervical dislocation, occipital hit, decapitation) influence the SP concentration in different ways. It is assumed SP concentration in plasma after cervical dislocation to be the best corresponding value for physiological conditions.

Anesthesia↗
PubMed1986

Energy dependence of protein translocation into chloroplasts.

The translocation of in vitro synthesized precursor proteins into intact spinach chloroplasts was investigated with respect to its energy requirement. It was demonstrated that MgATP itself, and not a transmembrane electrochemical gradient across the envelope membrane, promotes protein import. By manipulating the external and the stromal level of MgATP, we provided evidence that MgATP energized the protein import not within the chloroplast but at the outside of the envelope membrane. It is postulated that an MgATP-dependent phosphorylation/dephosphorylation cycle at the outer membrane face was involved in the course of protein translocation into the chloroplast.

Adenosine Triphosphate↗