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Small membrane protein regulator

Dekai Wang, Heqin Liu, Guowei Zhai, Liangsheng Wang, Jianfeng Shao, Yuezhi Tao
Functional chloroplast generation depends on the precise coordination of gene expression between the plastid and the nucleus and is essential for plant growth and development. In this study, a rice (Oryza sativa) mutant that exhibited albino and seedling-lethal phenotypes was isolated from a(60)Co-irradiated rice population. The mutant gene was identified as an ortholog of the Arabidopsis plastid transcriptionally active chromosome protein 2 (pTAC2) gene, and the mutant strain was designated osptac2. Sequence and transcription analyses showed that OspTAC2 encodes a putative chloroplast protein consisting of 10 pentratricopeptide repeat (PPR) domains and a C-terminal small MutS-related (SMR) domain...
September 15, 2016: Journal of Genetics and Genomics, Yi Chuan Xue Bao
Jessica M Wilson, Jeremy W Prokop, Ellen Lorimer, Elizabeth Ntantie, Carol L Williams
Two isoforms of the small GTPase Rap1, Rap1A and Rap1B, participate in cell adhesion; Rap1A promotes steady state adhesion, while Rap1B regulates dynamic changes in cell adhesion. These events depend on the prenylation of Rap1, which promotes its membrane localization. Here, we identify previously unsuspected differences in the regulation of prenylation of Rap1A versus Rap1B, due in part to their different phosphorylation-dependent interactions with the chaperone protein SmgGDS-607. Previous studies indicate that activation of Gαs protein-coupled receptors (GPCRs) phosphorylates S-179 and S-180 in the polybasic region (PBR) of Rap1B, which inhibits Rap1B binding to SmgGDS-607 and diminishes Rap1B prenylation and membrane localization...
October 16, 2016: Journal of Molecular Biology
Nigora Mukhamedova, Anh Hoang, Huanhuan L Cui, Irena Carmichael, Ying Fu, Michael Bukrinsky, Dmitri Sviridov
OBJECTIVE: ABCA1 (ATP-binding cassette transporter A1) is the principal protein responsible for cellular cholesterol efflux. Abundance and functionality of ABCA1 is regulated both transcriptionally and post-translationally, with endocytosis of ABCA1 being an important element of post-translational regulation. Functional ABCA1 resides on the plasma membrane but can be internalized and either degraded or recycled back to the plasma membrane. The interaction between the degradative and recycling pathways determines the abundance of ABCA1 and may contribute to the efflux of intracellular cholesterol...
October 6, 2016: Arteriosclerosis, Thrombosis, and Vascular Biology
K N Sathish Yadav, Dmitry A Semchonok, Lukáš Nosek, Roman Kouřil, Geoffrey Fucile, Egbert J Boekema, Lutz A Eichacker
Photosystem I (PSI) is a pigment-protein complex required for the light-dependent reactions of photosynthesis and participates in light-harvesting and redox-driven chloroplast metabolism. Assembly of PSI into supercomplexes with light harvesting complex (LHC) II, cytochrome b6f (Cytb6f) or NAD(P)H dehydrogenase complex (NDH) has been proposed as a means for regulating photosynthesis. However, structural details about the binding positions in plant PSI are lacking. We analyzed large data sets of electron microscopy single particle projections of supercomplexes obtained from the stroma membrane of Arabidopsis thaliana...
October 15, 2016: Biochimica et Biophysica Acta
Z Schultzhaus, T B Johnson, B D Shaw
Cell growth necessitates extensive membrane remodeling events including vesicle fusion or fission, processes that are regulated by coat proteins. The hyphal cells of filamentous fungi concentrate both exocytosis and endocytosis at the apex. This investigation focuses on clathrin in Aspergillus nidulans, with the aim of understanding its role in membrane remodeling in growing hyphae. We examined clathrin heavy chain (ClaH-GFP) which localized to three distinct subcellular structures: late Golgi (trans-Golgi equivalents of filamentous fungi), which are concentrated just behind the hyphal tip but are intermittently present throughout all hyphal cells; the region of concentrated endocytosis just behind the hyphal apex (the "endocytic collar"); and small, rapidly moving puncta that were seen trafficking long distances in nearly all hyphal compartments...
October 14, 2016: Molecular Microbiology
Li Chen, David R Brigstock
Liver fibrosis occurs during chronic injury and represents, in large part, an exaggerated matrigenic output by hepatic stellate cells (HSCs) which become activated as a result of injury-induced signaling pathways in parenchymal and inflammatory cells (hepatocytes, macrophages, etc.). The molecular components in these pathways (e.g., CCN proteins) are modulated by transcription factors as well as by factors such as microRNAs (miRs) that act posttranscriptionally. MiRs are small (~23 nt) noncoding RNAs that regulate gene expression by specifically interacting with the 3' untranslated region (UTR) of target gene mRNA to repress translation or enhance mRNA cleavage...
2017: Methods in Molecular Biology
Inken Lorenzen, Juliane Lokau, Yvonne Korpys, Mirja Oldefest, Charlotte M Flynn, Ulrike Künzel, Christoph Garbers, Matthew Freeman, Joachim Grötzinger, Stefan Düsterhöft
An important, irreversible step in many signalling pathways is the shedding of membrane-anchored proteins. A Disintegrin And Metalloproteinase (ADAM) 17 is one of the major sheddases involved in a variety of physiological and pathophysiological processes including regeneration, differentiation, and cancer progression. This central role in signalling implies that ADAM17 activity has to be tightly regulated, including at the level of localisation. Most mature ADAM17 is localised intracellularly, with only a small amount at the cell surface...
October 12, 2016: Scientific Reports
Huakun Zheng, Simiao Chen, Xiaofeng Chen, Shuyan Liu, Xie Dang, Chengdong Yang, Martha C Giraldo, Ely Oliveira-Garcia, Jie Zhou, Zonghua Wang, Barbara Valent
The Rab GTPase proteins play important roles in the membrane trafficking, and consequently protein secretion and development of eukaryotic organisms. However, little is known about the function of Rab GTPases in Magnaporthe oryzae. To further explore the function of Rab GTPases, we deleted the ortholog of the yeast Sec4p protein in M. oryzae, namely MoSEC4. The ΔMosec4 mutant is defective in polarized growth and conidiation, and it displays decreased appressorium turgor pressure and attenuated pathogenicity...
2016: Frontiers in Plant Science
Hong-Tai Tzeng, Yi-Ching Wang
A large group of small Rab GTPases which mediate secretory and endosomal membrane transport, as well as autophagosome biogenesis, are essential components of vesicle trafficking machinery. Specific Rab protein together with the cognate effectors coordinates the dynamics of trafficking pathway and determines the cargo proteins destination. Functional impairments of Rab proteins by mutations or post-translational modifications disrupting the regulatory network of vesicle trafficking have been implicated in tumorigenesis...
October 6, 2016: Journal of Biomedical Science
Chen Feng, Wei-Kiat Wee, Huizhi Chen, Li-Teng Ong, Jing Qu, Hui-Foon Tan, Suet-Mien Tan
Kindlins are a small family of 4.1-ezrin-radixin-moesin (FERM)-containing cytoplasmic proteins. Kindlin-3 is expressed in platelets, hematopoietic cells, and endothelial cells. Kindlin-3 promotes integrin activation, clustering and outside-in signaling. Aberrant expression of kindlin-3 was reported in melanoma and breast cancer. Intriguingly, kindlin-3 has been reported to either positively or negatively regulate cancer cell metastasis. In this study, we sought to clarify the expression of kindlin-3 in melanoma cells and its role in melanoma metastasis...
October 7, 2016: Cell Adhesion & Migration
Rosario Gajardo-Gómez, Valeria C Labra, Juan A Orellana
Under physiological conditions, microglia adopt a resting phenotype associated with the production of anti-inflammatory and neurotrophic factors. In response to a wide variety of insults, these cells shift to an activated phenotype that is necessary for the proper restoration of brain homeostasis. However, when the intensity of a threat is relatively high, microglial activation worsens the progression of damage rather than providing protection, with potentially significant consequences for neuronal survival...
2016: Frontiers in Molecular Neuroscience
Zahra Hemmatian, Scott Keene, Erik Josberger, Takeo Miyake, Carina Arboleda, Jessica Soto-Rodríguez, François Baneyx, Marco Rolandi
In biological systems, intercellular communication is mediated by membrane proteins and ion channels that regulate traffic of ions and small molecules across cell membranes. A bioelectronic device with ion channels that control ionic flow across a supported lipid bilayer (SLB) should therefore be ideal for interfacing with biological systems. Here, we demonstrate a biotic-abiotic bioprotonic device with Pd contacts that regulates proton (H(+)) flow across an SLB incorporating the ion channels Gramicidin A (gA) and Alamethicin (ALM)...
October 7, 2016: Nature Communications
Mridula Dwivedi, Roland Winter
Phosphoinositols are an important class of phospholipids that are involved in a myriad of cellular processes, from cell signaling to motility and adhesion. Vinculin (Vn) is a major adaptor protein that regulates focal adhesions in conjunction with PIP2 in lipid membranes and other cytoskeletal components. The binding and unbinding transitions of Vn at the membrane interface are an important link to understanding the coordination of cell signaling and motility. Using different biophysical tools, including atomic force microscopy combined with confocal fluorescence microscopy and Fourier transform infrared spectroscopy, we studied the nanoscopic interactions of activated and autoinhibited states of Vn with lipid membranes...
October 4, 2016: Biophysical Journal
Jennifer L Johnson, Mahalakshmi Ramadass, Jing He, Steven J Brown, Jinzhong Zhang, Lusine Abgaryan, Nikolaos Biris, Evripidis Gavathiotis, Hugh Rosen, Sergio D Catz
Neutrophils constitute the first line of cellular defense in response to bacterial and fungal infections and rely on granular proteins to kill microorganisms, but uncontrolled secretion of neutrophil cargos is injurious to the host and should be closely regulated. Thus, increased plasma levels of neutrophil secretory proteins including myeloperoxidase and elastase is associated with tissue damage and is a hallmark of systemic inflammation. Here, we describe a novel high-throughput screening approach to identify small-molecule inhibitors of the interaction between the small GTPase Rab27a and its effector JFC1, two central regulators of neutrophil exocytosis...
October 4, 2016: Journal of Biological Chemistry
Paul Linsdell
The main function of the cystic fibrosis transmembrane conductance regulator (CFTR) is as an ion channel for the movement of small anions across epithelial cell membranes. As an ion channel, CFTR must form a continuous pathway across the cell membrane-referred to as the channel pore-for the rapid electrodiffusional movement of ions. This review summarizes our current understanding of the architecture of the channel pore, as defined by electrophysiological analysis and molecular modeling studies. This includes consideration of the characteristic functional properties of the pore, definition of the overall shape of the entire extent of the pore, and discussion of how the molecular structure of distinct regions of the pore might control different facets of pore function...
October 3, 2016: Cellular and Molecular Life Sciences: CMLS
Kwang-Jin Cho, Darren E Casteel, Priyanka Prakash, Lingxiao Tan, Dharini van der Hoeven, Angela A Salim, Choel Kim, Robert J Capon, Ernest Lacey, Shane R Cunha, Alemayehu A Gorfe, John F Hancock
K-Ras must localize to the plasma membrane and be arrayed in nanoclusters for biological activity. We show here that K-Ras is a substrate for cyclic GMP-dependent protein kinases (PKGs). In intact cells activated PKG2 selectively co-localizes with K-Ras on the plasma membrane and phosphorylates K-Ras at Ser181 in the C-terminal polybasic domain. K-Ras phosphorylation by PKG2 is triggered by activation of AMP kinase and requires eNOS and soluble guanylyl-cyclase. Phosphorylated K-Ras re-organizes into distinct nanoclusters that retune signal output...
October 3, 2016: Molecular and Cellular Biology
Anna Bagnato, Laura Rosanò
Metastatization is a complex multistep process requiring fine-tuned regulated cytoskeleton re-modeling, mediated by the cross-talk of actin with interacting partners, such as the Rho GTPases. Our expanding knowledge of invadopodia, small invasive membrane protrusions composed of a core of F-actin, actin regulators and actin-binding proteins, and hotspots for secretion of extracellular matrix (ECM) proteinases, contributes to clarify critical steps of the metastatic program. Growth factor receptors and their intermediate signaling molecules, along with matrix adhesion and rigidity, pH and hypoxia, act as drivers of cytoskeleton changes and invadopodia formation...
October 3, 2016: Small GTPases
Otilia V Vieira
Disruption of the cell plasma membrane can occur due to mechanical damage, pore forming toxins, etc. Resealing or plasma membrane repair (PMR) is the emergency response required for cell survival. It is triggered by Ca(2+) entering through the disruption, causing organelles such as lysosomes located underneath the plasma membrane to fuse rapidly with the adjacent plasma membrane. We have recently identified some of the molecular traffic machinery that is involved in this vital process. Specifically, we showed that 2 members of the Rab family of small GTPases, Rab3a and Rab10, are essential for lysosome exocytosis and PMR in cells challenged with a bacterial toxin, streptolysin-O (SLO)...
September 29, 2016: Small GTPases
Zheng-Wei Li, Bin Wu, Pin Ye, Zhi-Yong Tan, Yong-Hua Ji
BACKGROUND: A previous study found that brain natriuretic peptide (BNP) inhibited inflammatory pain via activating its receptor natriuretic peptide receptor A (NPRA) in nociceptive sensory neurons. A recent study found that functional NPRA is expressed in almost all the trigeminal ganglion (TG) neurons at membrane level suggesting a potentially important role for BNP in migraine pathophysiology. METHODS: An inflammatory pain model was produced by subcutaneous injection of BmK I, a sodium channel-specific modulator from venom of Chinese scorpion Buthus martensi Karsch...
December 2016: Journal of Headache and Pain
Alberta Palazzo, Olivier Bluteau, Kahia Messaoudi, Francesco Marangoni, Yunhua Chang, Sylvie Souquere, Gérard Pierron, Valérie Lapierre, Yi Zheng, William Vainchenker, Hana Raslova, Najet Debili
BACKGROUND: Cytoskeleton rearrangements are essential in platelet release. The RHO small GTPase family, as regulators of the actin cytoskeleton, plays an important function in proplatelet formation. In the neuronal system, CDC42 is involved in the axone formation, a process that combined elongation and branching as proplatelet formation. OBJECTIVE: To analyze the role of CDC42 and its effectors of the WASP family on proplatelet formation METHODS: Human MKs were obtained from CD34(+) cells...
September 29, 2016: Journal of Thrombosis and Haemostasis: JTH
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