Cortexillins I and II of D. discoideum constitute a novel subfamily of proteins with actin-binding sites of the alpha-actinin/spectrin type. The C-terminal halves of these dimeric proteins contain a heptad repeat domain by which the two subunits are joined to form a two-stranded, parallel coiled coil, giving rise to a 19 nm tail. The N-terminal domains that encompass a consensus actin-binding s...

The gene encoding the spike glycoprotein of the human coronavirus HCV 229E has been cloned and sequenced. This analysis predicts an S polypeptide of 1173 amino acids with an Mr of 128,600. The polypeptide has 30 potential N-glycosylation sites. A number of structural features typical of coronavirus S proteins can be recognized, including a signal sequence, a membrane anchor, heptad repeat struc...

Membrane fusion between virus and host cells is the key step for enveloped virus entry and is mediated by the viral envelope fusion protein. In murine coronavirus, mouse hepatitis virus (MHV), the spike (S) protein mediates this process. Recently, the formation of anti-parallel 6-helix bundle of the MHV S protein heptad repeat (HR) regions (HR1 and HR2) has been confirmed, implying coronavirus ...

We are investigating the binding of a series of monoclonal antibodies to native and detergent-treated human T-lymphotropic virus I (HTLV-I) envelope proteins to explore their conformation. A comparison of our data with previously published findings suggests that a central neutralization domain (aa 175-200) is folded such that only short stretches are exposed at the surface of the native envelop...

Two algorithms for the efficient identification of segment neighborhoods are presented. A segment neighborhood is a set of contiguous residues that share common features. Two procedures are developed to efficiently find estimates for the parameters of the model that describe these features and for the residues that define the boundaries of each segment neighborhood. The algorithms can accept ne...

Many viral fusion-mediating glycoproteins couple alpha-helical bundle formation to membrane merger, but have different methods for fusion activation. To study paramyxovirus-mediated fusion, we mutated the SV5 fusion (F) protein at conserved residues L447 and I449, which are adjacent to heptad repeat (HR) B and bind to a prominent cavity in the HRA trimeric coiled coil in the fusogenic six-helix...

Controlled changes in mitochondrial morphology participate in cellular signaling cascades. However, the molecular mechanisms modifying mitochondrial shape are largely unknown. Here we show that the mitogen-activated protein (MAP) kinase cascade member extracellular-signal-regulated kinase (ERK) phosphorylates the pro-fusion protein mitofusin (MFN) 1, modulating its participation in apoptosis an...

There is good evidence for functional interactions between splicing and transcription in eukaryotes, but how and why these processes are coupled remain unknown. Prp5 protein (Prp5p) is an RNA-stimulated adenosine triphosphatase (ATPase) required for prespliceosome formation in yeast. We demonstrate through in vivo RNA labeling that, in addition to a splicing defect, the prp5-1 mutation causes a...

We determined that the tandem SH2 domain of S. cerevisiae Spt6 binds the linker region of the RNA polymerase II subunit Rpb1 rather than the expected sites in its heptad repeat domain. The 4 nM binding affinity requires phosphorylation at Rpb1 S1493 and either T1471 or Y1473. Crystal structures showed that pT1471 binds the canonical SH2 pY site while pS1493 binds an unanticipated pocket 70 Å di...