Import of honeybee prepromelittin into the endoplasmic reticulum

Honeybee prepromelittin is correctly processed and imported by dog pancreas microsomes. Insertion of prepromelittin into microsomal membranes, as assayed by signal sequence removal, does not depend on signal recognition particle (SRP) and docking protein. We addressed the question as to how prepromelittin bypasses the SRP/docking protein system. Hybrid proteins between prepromelittin, or carboxy-terminally truncated derivatives, and the cytoplasmic protein dihydrofolate reductase from mouse were constructed. These hybrid proteins were analysed for membrane insertion and sequestration into microsomes. The results suggest the following: (i) The signal sequence of prepromelittin is capable of interacting with the SRP/docking protein system, but this interaction is not mandatory for membrane insertion; this is related to the small size of prepromelittin. (ii) In prepromelittin a cluster of negatively charged amino acids must be balanced by a cluster of positively charged amino acids in order to allow membrane insertion. (iii) In general, a signal sequence can be sufficient to mediate membrane insertion independently of SRP and docking protein in the case of short precursor proteins; however, the presence and distribution of charged amino acids within the mature part of these precursors can play distinct roles

The Sulfonylurea Drug, Glimepiride, Stimulates Glucose Transport, Glucose Transporter Translocation, and Dephosphorylation In Insulin-Resistant Rat Adipocytes In Vitro

Sulfonylurea drugs are widely used in the therapy of NIDDM. The improvement of glucose tolerance after long-term treatment of NIDDM patients with the drug can be explained by stimulation of glucose utilization in peripheral tissues that are characterized by insulin resistance in these patients. We studied whether the novel sulfonylurea drug, glimepiride, stimulates glucose transport into isolated insulin-resistant rat adipocytes. After long-term incubation of the cells in primary culture with high concentrations of glucose, glutamine, and insulin, stimulation of glucose transport by insulin was significantly reduced both with respect to maximal responsiveness (65% decrease of Vmax) and sensitivity (2.6-fold increase of ED50) compared with adipocytes cultured in medium containing a low concentration of glucose and no insulin. This reflects insulin resistance of glucose transport. In contrast, both responsiveness and sensitivity of glucose transport toward stimulation by glimepiride were only marginally reduced in insulin-resistant adipocytes (15% decrease of Vmax; 1.2-fold increase of ED50) versus control cells. Glimepiride, in combination with glucose and glutamine during the primary culture, caused desensitization of the glucose transport system toward stimulation by insulin, but to a lesser degree than insulin itself (50% reduction of Vmax; ninefold increase of ED50). Again, the maximal responsiveness and sensitivity of glucose transport toward stimulation by glimepiride were only slightly diminished. The presence of glimepiride during primary culture did not antagonize the induction of insulin resistance of glucose transport. The stimulation of glucose transport in insulin-resistant adipocytes by glimepiride is caused by translocation of glucose transporters from low-density microsomes to plasma membranes as demonstrated by subcellular fractionation and immunoblotting with anti-GLUT1 and anti-GLUT4 antibodies. Immunoprecipitation of GLUT4 from 32Pi- and [35S]methionine-labeled adipocytes revealed that the insulin resistance of GLUT4 translocation is accompanied by increased (three- to fourfold) phosphorylation of GLUT4 in both low-density microsomes and plasma membranes. Short-term treatment of desensitized adipocytes with glimepiride or insulin reduced GLUT4 phosphorylation by ∼70 and 25%, respectively, in both fractions. We conclude that glimepiride activates glucose transport by stimulation of GLUT1 and GLUT4 translocation in rat adipocytes via interference at a site downstream of the putative molecular defect in the signaling cascade between the insulin receptor and the glucose transport system induced by high concentrations of glucose and insulin. The molecular site of glimepiride action is related to GLUT4 phosphorylation/dephosphorylation, which may regulate glucose transporter activity and translocation. These in vitro findings implicate an additional mode of sulfonylurea action in the improvement of glucose tolerance of NIDDM patients.</jats:p

ooRexx 5 Yielding Swiss Army Knife Usability

The new version 5.0 of the message based object-oriented programming language ooRexx ("open object-oriented REXX") is easy to learn, yet powerful. This article introduces some of the new language features with nutshell examples that at the same time demonstrate its power when deployed in different operating system environments. The modern native API of ooRexx makes it in addition very easy to extend the language with new functionality and deploy it as a macro language for any C++-based application

Cyclic AMP Receptor Protein from Yeast Mitochondria

We have identified and characterized a cyclic AMP receptor protein in mitochondria of the yeast Saccharomyces cerevisiae. The binding is specific for cyclic nucleotides, particularly for cyclic AMP which is bound with high affinity (Kd of 10(-9) M) at 1 to 5 pmol/mg of mitochondrial protein. The mitochondrial cyclic AMP receptor is synthesized on cytoplasmic ribosomes and has an apparent molecular weight of 45,000 as determined by photoaffinity labeling. It is localized in the inner mitochondrial membrane and faces the intermembrane space. Cross-contamination of mitochondrial inner membranes by plasma membranes or soluble cytoplasmic proteins is excluded

Wiederfund der Steinbeere (Rubus saxatilis L.) in Südwestniedersachsen

Die Bestandsentwicklung der Steinbeere (Rubus saxatilis L.) im Weser-Ems-Gebiet wird beschrieben, ihr Wiederfund im Gehn sowie im Hüggel bei Osnabrück kurz dargestellt und ihre Gesellschaft diskutiert.The text is a description of the stock of the Stone Bramble (Rubus saxatilis L.) in the Weser- Ems area and its association as weil as its recovery in the Gehn Hills and the Hüggel Hill

Security-sensitive tackling of obstructed workflow executions

Imposing access control onto workflows considerably reduces the set of users authorized to execute the workflow tasks. Further constraints (e.g. Separation of Duties) as well as unexpected unavailabilty of users may finally obstruct the successful workflow execution. To still complete the execution of an obstructed workflow, we envisage a hybrid approach. If a log is provided, we partition its traces into “successful” and “obstructed” ones by analysing the given workflow and its authorizations. An obstruction should then be solved by finding its nearest match from the list of successful traces. If no log is provided, we flatten the workflow and its authorizations into a Petri net and encode the obstruction with a corresponding “obstruction marking”. The structural theory of Petri nets shall then be tweaked to provide a minimized Parikh vector, that may violate given firing rules, however reach a complete marking and by that, complete the workflow.Peer ReviewedPostprint (published version