Cell
Localized expression of decapentaplegic (dpp) is required for proper development of the Drosophila imaginal discs. Using genetic mosaics, we show that in the anterior compartment of appendage discs and anterior to the morphogenetic furrow in the eye disc, cells that lack CAMP-dependent protein kinase (PKA) activity ectopically express dpp. Pka - cells can influence the fate of neighboring...
The Drosophila hedgehog (hh) gene encodes a secreted protein involved in organizing growth and patterning in many developmental processes. Hh appears to act by inducing the localized expression of at least two other signaling molecules, decapentaplegic (dpp) and wingless (wg), which then govern cell proliferation and patterning in surrounding tissue. Here, we demonstrate that cyclic AMP (cAMP)-dependent...
The silent mating loci and chromosomal regions adjacent to telomeres of S. cerevisiae have features similar to heterochromatin of more complex eukaryotes. Transcriptional repression at these sites depends on the silent information regulators SIR3 and SIR4 as well as histones H3 and H4. We show here that the SIR3 and SIR4 proteins interact with specific silencing domains of the H3 and H4 N-termini...
We have developed a PCR assay that can detect a single Epstein-Barr virus (EBV) genome in the presence of 10 6 uninfected cells. Using this assay, we demonstrate that EBV persists, in the peripheral blood of all seropositive individuals tested, in CD19 + , CD23 - , and CD80 (B7) - B cells. We further show that the virus in these cells is latent, but readily reactivated...
The crystal structure of the replication terminator protein (RTP) of B. subtilis has been determined at 2.6 A resolution. As previously suggested by both biochemical and biophysical studies, the molecule exists as a symmetric dimer and is in the α+β protein-folding class. The protein has several uncommon features, including an antiparallel coiled-coil, which serves as the dimerization domain, and...
Reduced protein kinase A (PKA) activity in anterior imaginal disc cells leads to cell-autonomous induction of decapentaplegic (dpp), wingless (wg), and patched (ptc) transcription that is independent of hedgehog (hh) gene activity. The resulting nonautonomous adult wing and leg pattern duplications are largely due to induced dpp and wg expression and resemble phenotypes elicited by ectopic hh expression...
We report the identification of ligands for Tyro 3 (alternatively called Sky, rse, brt, or tif) and Axl (alternatively, Ark or UFO), members of a previously orphan family of receptor-like tyrosine kinases. These ligands correspond to protein S, a protease regulator that is a potent anticoagulant, and Gas6, a protein related to protein S but lacking any known function. Our results are reminiscent of...
We have determined the high resolution crystal structure of the A domain from the a chain of integrin CR3. The domain adopts a classic α/β ''Rossmann'' fold and contains an unusual Mg 2 + coordination site at its surface. One of the coordinating ligands is the glutamate side chain from another A domain molecule. We suggest that this site represents a general metal ion-dependent adhesion...
We have developed a generalized approach, using two hybrid interactions, to isolate Ha-Ras effector loop mutations that separate the ability of Ha-Ras to interact with different downstream effectors. These mutations attenuate or eliminate Ha-ras(G12V) transformation of mammalian cells, but retain complementary activity, as demonstrated by synergistic induction of foci of growth-transformed cells,...
Alphaviruses are a group of icosahedral, positive-strand RNA, enveloped viruses. The membrane bilayer, which surrounds the ~ 400 A diameter nucleocapsid, is penetrated by 80 spikes arranged in a T = 4 lattice. Each spike is a trimer of heterodimers consisting of glycoproteins Ell and E2. Cryoelectron microscopy and image reconstruction of Ross River virus showed that the T=4 quaternary structure of...
A novel murine plasma membrane protein has been identified in subpopulations of macrophages. It has an intracellular N-terminal domain, a transmembrane domain, and an extracellular region with a short spacer, an 89 Gly-Xaa-Yaa repeat-containing collagenous domain, and a C-terminal cysteine-rich domain. In situ hybridization and immunohistochemical staining have localized the protein to a subset of...
Signal transduction molecules within the two-component family represent a conserved adaptation for the control of genes involved in pathogenesis. The Bordetella virulence control locus, bvgAS, activates and represses gene expression in response to environmental signals. While infection requires virulence gene activation, the role of gene repression during infection is not understood. By altering regulatory...
We have cloned the cDNA encoding IκB-β, one of the two major IκB isoforms in mammalian cells. The recombinant IκB-β protein interacts with equal affinity to p65 and c-Rel and does not exhibit a preference between these Rel proteins. Instead the primary difference between IκB-α and IκB-β is in their response to different inducers of NF-κB activity. One class of inducers causes rapid but transient activation...
The bHLH-ZIP protein Mad heterodimerizes with Max as a sequence-specific transcriptional repressor. Mad is rapidly induced upon differentiation, and the associated switch from Myc-Max to Mad-Max heterocomplexes seem to repress genes normally activated by Myc-Max. We have identified two related mammalian cDNAs that encode Mad-binding proteins. Both possess sequence homology with the yeast transcription...