Darlene Chen

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The HIV-1 accessory protein Vif (virion infectivity factor) is required for the production of infectious virions by CD4(+) lymphocytes. Vif facilitates particle infectivity by blocking the inhibitory activity of APOBEC3G (CEM15), a virion-encapsidated cellular protein that deaminates minus-strand reverse transcript cytosines to uracils. We report that HIV-1(More)
In the human genome the apolipoprotein B mRNA-editing enzyme catalytic polypeptide (APOBEC)3 gene has expanded into a tandem array of genes termed APOBEC3A-G. Two members of this family, APOBEC3G and APOBEC3F, have been found to have potent activity against virion infectivity factor deficient (Deltavif) human immunodeficiency virus 1 (HIV-1). These enzymes(More)
The virion infectivity factor (Vif) accessory protein of HIV-1 forms a complex with the cellular cytidine deaminase APOBEC3G (apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3G) to block its antiviral activity. The antiviral property of APOBEC3G is conserved in several mammalian species, but the ability of Vif to block this activity is(More)
Hepatic cytochrome P450 (CYP) genes, including members of CYP1 to CYP4 families, comprise the majority of the CYP gene superfamily. Previous study has demonstrated that HepG2-specific transcriptional activation of two CYP2C genes was dependent on a common element that bound a HepG2 nuclear protein designated HPF-1 (Venepally, P., Chen, D., and Kemper, B.(More)
The myasthenic syndrome due to abnormal acetylcholine resynthesis is characterized by early onset, recessive inheritance, and recurrent episodes of potentially fatal apnea. Mutations in the gene encoding choline acetyltransferase (CHAT) have been found to account for this condition. We have identified five patients from three independent families with(More)
A functional binding site for a liver-enriched transcription factor, hepatocyte nuclear factor-4 (HNF-4), has previously been identified around -100 in the CYP2C2 promoter and proposed to be a common regulatory motif for the hepatic expression of many CYP2 genes. The transcriptional activity of the proximal promoters of three closely related cytochrome P450(More)
To analyze the transcriptional regulatory elements in rabbit cytochrome P450IIC genes, varying lengths of the 5'-flanking regions of CYP2C1 and CYP2C2 were fused to a luciferase reporter gene. Promoter activity was assayed by transfection into HepG2 cells, a hepatic cell line, and monkey kidney COS-1 cells, a nonhepatic cell line. Activity of the CYP2C1(More)
The first step in V(D)J recombination is the formation of specific DNA double-strand breaks (DSBs) by the RAG1 and RAG2 proteins, which form the RAG recombinase. DSBs activate a complex network of proteins termed the DNA damage response (DDR). A key early event in the DDR is the phosphorylation of histone H2AX around DSBs, which forms a binding site for the(More)
To investigate the dependence of transmembrane translocation on the hydrophobic moment of the hydrophobic core of the preproparathyroid hormone signal sequence, amino acids were switched to maximize or minimize the hydrophobic moment without changing the length or overall hydrophobicity of the core. As assayed in an in vitro translation system with(More)
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