The group of Prof. Dr. Ralf Erdmann at the Ruhr-Universitt Bochum (Faculty of Medicine, Department of Systems Biochemistry) discovered a connection of peroxisomal protein import and receptor export. In the Journal of Biological Chemistry, they disclosed that enzymes only get imported into certain cell organelles (peroxisomes) upon coupling of their import to the recycling of their transport protein (receptor).
Multi-functional tool peroxisome
Peroxisomes do not have their own DNA. Thus, all peroxisomal proteins are coded within the nucleus and imported into the peroxisome after their synthesis is completed. The Erdmann lab investigates this process in detail. Peroxisomes contain more than 50 various enzymes in total which e.g. decompose fatty acids and dispose hydrogen peroxide or plasmalogens, the main phospholipid of the white matter of the brain. A disruption of their function does not only cause severe metabolic disorders, it can even lead to death of newborns.
Export signal controls recycling
Dynamic receptors recognize and escort the enzymes destined for the peroxisome to the organelle where they attach to the membrane. Then the receptor-enzyme complex disassembles and the enzyme is transported across the peroxisomal membrane. Afterwards, the receptor is transported from the membrane back to the cytosol. This recycling is controlled by the attachment of the small protein ubiquitin to the receptor, which functions as an export signal.
Modification as a safety barrier
The team of Prof. Dr. Ralf Erdmann studied a certain peroxisomal receptor, which consists of a targeting unit (Pex18p) and an enzyme-binding unit (Pex7p). The scientists discovered that ubiquitin modifies Pex18p in order to enable the receptor to return to the intracellular liquid. Only when the targeting unit of the receptor is exported from the membrane, the import of the cargo-loaded enzyme-binding unit tak
'/>"/>
| Contact: Dr. Ralf Erdmann Ralf.Erdmann@rub.de 49-234-322-4943 Ruhr-University Bochum Source:Eurekalert |
Related biology news :
1. Computer order entry systems reduce preventable adverse drug events
2. Entry point for hepatitis C infection identified
3. SIB launches next generation ExPASy, an entry portal to indispensable bioinformatics resources
4. Entry inhibitors show promise as drugs with new MOA for treatment of HBV and HDV infection
5. No-entry zones for AIDS virus
6. Potatoes lower blood pressure in people with obesity and hypertension without increasing weight
7. No future without scarce metals
8. System to deliver organ transplant drug -- without harmful side effects
9. A new method for testing allergenic substances without experimental animals
10. Green routing can cut car emissions without significantly slowing travel time
11. Alternate ending -- living on without telomerase
| Copyright © 2003-2012 Bio-Medicine. All rights reserved. ABOUT | CONTACT US | DISCLAIMER | PRIVACY POLICY | TERMS AND CONDITIONS |  |