Receptor-like kinase FERONIA (FER) plays a crucial role in plant response to small molecule hormones [e.g., auxin and abscisic acid (ABA)] and peptide signals [e.g., rapid alkalinization factor (RALF)]. It remains unknown how FER integrates these different signaling events in the control of cell growth and stress responses. Under stress conditions, increased levels of ABA will inhibit cell elongation in the roots. In our previous work, we have shown that FER, through activation of the guanine nucleotide exchange factor 1 (GEF1)/4/10-Rho of Plant 11 (ROP11) pathway, enhances the activity of the phosphatase ABA Insensitive 2 (ABI2), a negative regulator of ABA signaling, thereby inhibiting ABA response. In this study, we found that both RALF and ABA activated FER by increasing the phosphorylation level of FER. The FER loss-of-function mutant displayed strong hypersensitivity to both ABA and abiotic stresses such as salt and cold conditions, indicating that FER plays a key role in ABA and stress responses. We further showed that ABI2 directly interacted with and dephosphorylated FER, leading to inhibition of FER activity. Several other ABI2-like phosphatases also function in this pathway, and ABA-dependent FER activation required PYRABACTIN RESISTANCE (PYR)/PYR1-LIKE (PYL)/REGULATORY COMPONENTS OF ABA RECEPTORS (RCAR)-A-type protein phosphatase type 2C (PP2CA) modules. Furthermore, suppression of RALF1 gene expression, similar to disruption of the FER gene, rendered plants hypersensitive to ABA. These results formulated a mechanism for ABA activation of FER and for cross-talk between ABA and peptide hormone RALF in the control of plant growth and responses to stress signals.signal transduction | root growth | plant hormones

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This study indicates that a neural prosthetic device based on pudendal nerve stimulation might be developed to restore micturition function for people with SCI.

Detergents have been widely used for the solubilization of membrane proteins and the improvement of their digestion. In this paper, we have evaluated the application of sodium deoxycholate (SDC) to the solubilization and digestion of rat hippocampal plasma membrane (PM) proteins. For in-solution digestion, rat hippocampal PM fraction from sucrose-density gradient centrifugation was solubilized by boiling in 1.0% SDC, and directly digested without dilution. During the in-gel digestion of the hippocampal PM proteins separated by SDS-PAGE, 0.1% SDC was added. Before analysis of peptide mixture by liquid chromatography and electrospray mass spectrometry, SDC in the tryptic digests was removed by centrifugation following acidification. Use of 1.0% SDC in solubilization and in-solution digestion of rat PM proteins had led to 77 PM or membrane-associated proteins identified, a more than 2-fold increase over that by use of SDS. The addition of 0.1% SDC to the in-gel digestion of SDS-PAGE-resolved membrane proteins remarkably enhanced the coverage of tryptic peptides and the number of hydrophobic membrane proteins identified. Being a cheaper and more tractable acid-insoluble detergent, SDC could be used at higher concentration in the solubilization and tryptic digestion of proteins including PM proteins with the purpose of enhancing the protein solubility and at the same time making no interference with trypsin activity and subsequent analyses.

To comprehensively identify proteins of the rat liver plasma membrane (PM), we have adopted a proteomics strategy that utilizes sucrose density centrifugation in conjunction with aqueous two-phase partition for plasma membrane isolation, followed by SDS-PAGE, mass spectrometry and bioinformatics. Western blot analysis showed that this method results in highly purified plasma membrane fractions, which is a key to successful plasma membrane proteomics. The PM proteins were separated by SDS-PAGE and digested with trypsin. Through nano-ESI-LC MS/MS analysis we identified 428 rat liver membrane proteins, of which 304 had a gene ontology (GO) annotation indicating a cellular component, and 204 (67%) of the latter were known integral membrane proteins or membrane-associated proteins. In addition to proteins known to be associated with the plasma membrane, several hypothetical proteins have also been identified. This study not only provides a tool to study plasma membrane proteins with low levels of contamination, but also provides a data set for proteins of high to moderate abundance in rat liver plasma membranes, thus allowing for more comprehensive characterization of membrane proteins and a better understanding of membrane dynamics.