Receptor Membrane Ring-H2 (RMR) Proteins in Plants

In plant cells it has been demonstrated that many vacuolar proteins are sorted to their final destination by cargo receptors. These receptors are transmembrane proteins able to bind soluble vacuolar proteins determining their transport to vacuoles. This study is focused on AtRMR, a family of putative receptors composed of six genes in Arabidopsis thaliana. These experiments showed that AtRMR1 localizes in the trans-Golgi network while AtRMR2 localizes in the endoplasmic reticulum. This different localization is due to a putative localization signal present in the AtRMR1 linker. Also this study demonstrated that AtRMR1 can make homodimers and can interact with AtRMR2 making heterodimers. These dimers localize in the trans-Golgi network. Finally the transmembrane and the linker are probably the domains involved in protein-protein interaction. This book provided new information about the physiology of AtRMR traffic and dimerization, improving the comprehension of the mechanisms and the localization signals involved in protein sorting to vacuoles. Therefore this book should be useful for plant biologists or anyone else is interested in protein trafficking in plant secretory pathway.