Given an elliptic curve E1 over a number field K and an element s in its 2-Selmer group, we give two different ways to construct infinitely many Abelian surfaces A such that the homogeneous space representing s occurs as a fibre of A over another elliptic curve E2. We show that by comparing the 2Selmer groups of E1, E2 and A, we can obtain information about X(E1/K)[2] and we give examples where...

The alphavirus Semliki Forest virus (SFV) matures by budding at the cell surface. This process is driven by interactions of its membrane protein heterodimer E2-E1 and the nucleocapsid. The virus penetrates into new cells by an E1-mediated membrane fusion event. The E1 subunit has a short, strongly positively charged cytoplasmic tail peptide (Arg-Arg) which is very conserved among different alph...

Cells colicinogenic for the colicin plasmids E1 or E2 (Col E1 and Col E2, respectively) were selected for a loss of colicin production after infection with bacteriophage Mu. Extrachromosomal deoxyribonucleic acid that was larger than the original colicin plasmids was found in such cells. A small insertion mutant in Col E1 deoxyribonucleic acid affecting active colicin production without affecti...

UNLABELLED In hepatitis C virus (HCV)-infected cells, the envelope glycoproteins E1 and E2 assemble as a heterodimer. To investigate potential changes in the oligomerization of virion-associated envelope proteins, we performed SDS-PAGE under reducing conditions but without thermal denaturation. This revealed the presence of SDS-resistant trimers of E1 in the context of cell-cultured HCV (HCVcc)...

UNLABELLED The human papillomavirus (HPV) E1 helicase promotes viral DNA replication through its DNA unwinding activity and association with host factors. The E1 proteins from anogenital HPV types interact with the cellular WD repeat-containing factor UAF1 (formerly known as p80). Specific amino acid substitutions in E1 that impair this interaction inhibit maintenance of the viral episome in im...

The interaction of an 18-base cis-element in the 5'-untranslated region of human folate receptor (FR)-alpha mRNA with a cytosolic trans-factor protein is critical for the translation of FR (Sun, X.-L., and Antony, A. C. (1996) J. Biol. Chem. 271, 25539-25547). This trans-factor was isolated to apparent homogeneity as a 43- and 38-kDa doublet from human placenta using poly(U)-Sepharose, followed...

Kv2.1 is a major delayed rectifying K(+) channel normally localized to highly phosphorylated somatodendritic clusters in neurons. Excitatory stimuli induce calcineurin-dependent dephosphorylation and dispersal of Kv2.1 clusters, with a concomitant hyperpolarizing shift in the channel's activation kinetics. We showed previously that sublethal ischemia, which renders neurons transiently resistant...

Microsomal epoxide hydrolase (EPHX1) catalyzes hydration reactions that determine the cellular disposition of reactive epoxide derivatives. Whereas the previously defined EPHX1 exon 1 sequence (E1) is derived from a promoter proximal to exon 2 of the EPHX1 coding region, in this investigation, we identified an alternative EPHX1 exon 1 sequence, E1-b, originating from a gene promoter localized a...

Regulation of the branched chain alpha-ketoacid dehydrogenase complex, the rate-limiting enzyme of branched chain amino acid catabolism, involves phosphorylation of 2 amino acid residues (site 1, serine 293; site 2, serine 303). To directly assess the roles played by these sites, site-directed mutagenesis was used to convert these serines to glutamates and/or alanines. Functional E1 heterotetra...

Papillomaviruses maintain their genomes in a relatively constant copy number as stable extrachromosomal plasmids in the nuclei of dividing host cells. The viral initiator of replication, E1, is not detected in papillomavirus-infected cells. Here, we present evidence that E1 encoded by bovine papillomavirus type 1 is an unstable protein that is degraded through the ubiquitin-proteasome pathway. ...