16 research outputs found
Localization and topology of ratp28, a member of a novel family of putative steroid-binding proteins
We have cloned ratp28, a membrane protein from rat liver homologous to the previously described hpr6.6, a putative steroid-binding protein in humans. Ratp28 has a type II topology as determined by protease digestion experiments on intact and detergent-solubilized membranes. Subcellular fractionation by sucrose density centrifugation revealed a distribution for ratp28 identical to Bip as a marker for membranes of the endoplasmic reticulum. In these experiments no association was found with markers for Golgi or plasma membranes, indicating that ratp28 is localized to the endoplasmic reticulum
Direct transfer of zinc between plants is channelled by common mycorrhizal network of arbuscular mycorrhizal fungi and evidenced by changes in expression of zinc transporter genes in fungus and plant
The role that common mycorrhizal networks (CMNs) play in plantâtoâplant transfer of zinc (Zn) has not yet been investigated, despite the proved functions of arbuscular mycorrhizal fungi (AMF) in crop Zn acquisition. Here, two autotrophic Medicago truncatula plants were linked by a CMN formed by Rhizophagus irregularis. Plants were grown in vitro in physically separated compartments (DonorâC and ReceiverâC) and their connection ensured only by CMN. A symbiosisâdefective mutant of M. truncatula was used as control in ReceiverâC. Plants in both compartments were grown on Znâfree medium, and only the leaves of the donor plants were Zn fertilized. A direct transfer of Zn was demonstrated from donor leaves to receiver shoots mediated by CMN. Direct transfer of Zn was supported by changes in the expression of fungal genes, RiZRT1 and RiZnT1, and plant gene MtZIP2 in roots and MtNAS1 in roots and shoots of the receiver plants. Moreover, Zn transfer was supported by the change in expression of MtZIP14 gene in AM fungal colonized roots. This work is the first evidence of a direct Zn transfer from a donor to a receiver plant via CMN, and of a triggering of transcriptional regulation of fungalâplant genes involved in Zn transportârelated processes