Gα12 and Gα13 subunits define a fourth class of G protein α subunits

Heterotrimeric guanine nucleotide-binding regulatory proteins (G proteins) are central to the signaling processes of multicellular organisms. We have explored the diversity of the G protein subunits in mammals and found evidence for a large family of genes that encode the α subunits. Amino acid sequence comparisons show that the different alpha subunits fall into at least three classes. These classes have been conserved in animals separated by considerable evolutionary distances; they are present in mammals, Drosophila, and nematodes. We have now obtained cDNA clones encoding two murine alpha subunits, Gα12 and Gα13, that define a fourth class. The translation products are predicted to have molecular masses of 44 kDa and to be insensitive to ADP-ribosylation by pertussis toxin. They share 67% amino acid sequence identity with each other and less than 45% identity with other α subunits. Their transcripts can be detected in every tissue examined, although the relative levels of the Gα13 message appear somewhat variable

Diversity of the G-protein family: sequences from five additional α subunits in the mouse

Biochemical analysis has revealed a number of guanine nucleotide-binding regulatory proteins (G proteins) that mediate signal transduction in mammalian systems. Characterization of their cDNAs uncovered a family of proteins with regions of highly conserved amino acid sequence. To examine the extent of diversity of the G protein family, we used the polymerase chain reaction to detect additional gene products in mouse brain and spermatid RNA that share these conserved regions. Sequences corresponding to six of the eight known G protein alpha subunits were obtained. In addition, we found sequences corresponding to five newly discovered alpha subunits. Our results suggest that the complexity of the G protein family is much greater than previously suspected

Alternative splicing produces transcripts encoding two forms of the α subunit of GTP-binding protein G_o

The α subunit of the guanine nucleotide-binding protein G_o ("o" for other) is believed to mediate signal transduction between a variety of receptors and effectors. cDNA clones encoding two forms of G_o α subunit were isolated from a mouse brain library. These two forms, which we call G_(o)Aα and G_(o)Bα, appear to be the products of alternative splicing. G_(o)Aα differs from G_(o)Bα over the C-terminal third of the deduced protein sequence. Both forms are predicted to be substrates for ADP-ribosylation by pertussis toxin. G_(o)Aα transcripts are present in a variety of tissues but are most abundant in brain. The G_(o)Bα transcript is expressed at highest levels in brain and testis. It is possible that G_(o)Aα and G_(o)Bα have different functions

Structural Arrangements of Polymers Adsorbed at Nanostrings

We study ground states of a hybrid system consisting of a polymer and an attractive nanowire by means of computer simulations. Depending on structural and energetic properties of the substrate, we find different adsorbed polymer conformations, amongst which are spherical droplets attached to the wire and monolayer tubes surrounding it. We construct the complete conformational phase diagram and analyze in more detail particularly interesting polymer-tube conformations.Comment: Proceedings of the 23nd Workshop on Recent Developments in Computer Simulation Studies in Condensed Matter Physics, Feb 22-26, 2010, Athens, Georgia, US

Characterization of G-protein α subunits in the Gq class: expression in murine tissues and in stromal and hematopoietic cell lines

Murine Gα14 and Gα15 cDNAs encode distinct α subunits of heterotrimeric guanine nucleotide-binding proteins (G proteins). These alpha subunits are related to members of the Gq class and share certain sequence characteristics with Gαq, Gα11, and Gα16, such as the absence of a pertussis toxin ADP-ribosylation site. Gα11 and Gαq are ubiquitously expressed among murine tissues but G alpha 14 is predominantly expressed in spleen, lung, kidney, and testis whereas Gα15 is primarily restricted to hematopoietic lineages. Among hematopoietic cell lines, Gα11 mRNA is found in all cell lines tested, Gαq is expressed widely but is not found in most T-cell lines, Gα15 is predominantly expressed in myeloid and B-cell lineages, and Gα14 is expressed in bone marrow adherent (stromal) cells, certain early myeloid cells, and progenitor B cells. Polyclonal antisera produced from synthetic peptides that correspond to two regions of Gα15 react with a protein of 42 kDa expressed in B-cell membranes and in Escherichia coli transformed with Gα15 cDNA. The expression patterns that were observed in mouse tissues and cell lines indicate that each of the alpha subunits in the Gq class may be involved in pertussis toxin-insensitive signal-transduction pathways that are fundamental to hematopoietic cell differentiation and function

Identification of Dictyostelium G_ɑ genes expressed during multicellular development

Guanine nucleotide-binding protein (G protein)-mediated signal transduction constitutes a common mechanism by which cells receive and respond to a diverse set of environmental signals. Many of the signals involved in the developmental life cycle of the slime mold Dictyostelium have been postulated to be transduced by such pathways and, in some cases, these pathways have been demonstrated to be dependent on specific G proteins. Using the polymerase chain reaction, we have identified two additional Dictyostelium G_ɑ genes, G_ɑ4 and G_ɑ5, that are developmentally regulated. Transcripts from both of these genes are primarily expressed during the multicellular stages of development, suggesting possible roles in cell differentiation or morphogenesis. The entire G_ɑ 4 gene was sequenced and found to encode a protein consisting of 345 amino acids. The G_ɑ4 subunit is homologous to other previously identified G_ɑ subunits, including the Dictyostelium Gɑ1 (43% identity) and G_ɑ2 (41% identity) subunits. However, the G_ɑ4 subunit contains some unusual sequence divergences in residues highly conserved among most eukaryotic G_ɑ subunits, suggesting that G_ɑ4 may be a member of another class of G_ɑ subunits

Systematic Microcanonical Analyses of Polymer Adsorption Transitions

In detailed microcanonical analyses of densities of states obtained by extensive multicanonical Monte Carlo computer simulations, we investigate the caloric properties of conformational transitions adsorbing polymers experience near attractive substrates. For short chains and strong surface attraction, the microcanonical entropy turns out to be a convex function of energy in the transition regime, indicating that surface-entropic effects are relevant. Albeit known to be a continuous transition in the thermodynamic limit of infinitely long chains, the adsorption transition of nongrafted finite-length polymers thus exhibits a clear signature of a first-order-like transition, with coexisting phases of adsorbed and desorbed conformations. Another remarkable consequence of the convexity of the microcanonical entropy is that the transition is accompanied by a decrease of the microcanonical temperature with increasing energy. Since this is a characteristic physical effect it might not be ignored in analyses of cooperative macrostate transitions in finite systems.Comment: 8 pages, 6 figure

Molecular Valves for Controlling Gas Phase Transport Made from Discrete Angstrom-Sized Pores in Graphene

An ability to precisely regulate the quantity and location of molecular flux is of value in applications such as nanoscale 3D printing, catalysis, and sensor design. Barrier materials containing pores with molecular dimensions have previously been used to manipulate molecular compositions in the gas phase, but have so far been unable to offer controlled gas transport through individual pores. Here, we show that gas flux through discrete angstrom-sized pores in monolayer graphene can be detected and then controlled using nanometer-sized gold clusters, which are formed on the surface of the graphene and can migrate and partially block a pore. In samples without gold clusters, we observe stochastic switching of the magnitude of the gas permeance, which we attribute to molecular rearrangements of the pore. Our molecular valves could be used, for example, to develop unique approaches to molecular synthesis that are based on the controllable switching of a molecular gas flux, reminiscent of ion channels in biological cell membranes and solid state nanopores.Comment: to appear in Nature Nanotechnolog

Questioning the rise of gelatinous zooplankton in the World's oceans

During the past several decades, high numbers of gelatinous zooplankton species have been reported in many estuarine and coastal ecosystems. Coupled with media-driven public perception, a paradigm has evolved in which the global ocean ecosystems are thought to be heading toward being dominated by “nuisance” jellyfish. We question this current paradigm by presenting a broad overview of gelatinous zooplankton in a historicalcontext to develop the hypothesis that population changes reflect the human-mediated alteration of global ocean ecosystems. To this end, we synthesize information related to the evolutionary context of contemporary gelatinous zooplankton blooms, the human frame of reference forchanges in gelatinous zooplankton populations, and whether sufficient data are available to have established the paradigm. We conclude that the current paradigm in which it is believed that there has been a global increase in gelatinous zooplankton is unsubstantiated, and we develop a strategy for addressing the critical questions about long-term, human-related changes in the sea as they relate to gelatinous zooplankton blooms

Transcriptome Analysis and SNP Development Can Resolve Population Differentiation of Streblospio benedicti, a Developmentally Dimorphic Marine Annelid

Next-generation sequencing technology is now frequently being used to develop genomic tools for non-model organisms, which are generally important for advancing studies of evolutionary ecology. One such species, the marine annelid Streblospio benedicti, is an ideal system to study the evolutionary consequences of larval life history mode because the species displays a rare offspring dimorphism termed poecilogony, where females can produce either many small offspring or a few large ones. To further develop S. benedicti as a model system for studies of life history evolution, we apply 454 sequencing to characterize the transcriptome for embryos, larvae, and juveniles of this species, for which no genomic resources are currently available. Here we performed a de novo alignment of 336,715 reads generated by a quarter GS-FLX (Roche 454) run, which produced 7,222 contigs. We developed a novel approach for evaluating the site frequency spectrum across the transcriptome to identify potential signatures of selection. We also developed 84 novel single nucleotide polymorphism (SNP) markers for this species that are used to distinguish coastal populations of S. benedicti. We validated the SNPs by genotyping individuals of different developmental modes using the BeadXPress Golden Gate assay (Illumina). This allowed us to evaluate markers that may be associated with life-history mode