Derek Hewgill

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The negative regulation of T- or B-cell antigen receptor signaling by CD5 was proposed based on studies of thymocytes and peritoneal B-1a cells from CD5-deficient mice. Here, we show that CD5 is constitutively associated with phosphotyrosine phosphatase activity in Jurkat T cells. CD5 was found associated with the Src homology 2 (SH2) domain containing(More)
A molecular probe was developed to monitor caspase activity in living cells by flow cytometry. It consists of CFP and YFP with a peptide linker containing two caspase-cleavage sites (LEVD). Its expression resulted in intense fluorescence resonance energy transfer (FRET), whereas cleavage of this linker by caspases eliminated FRET because of physical(More)
The availability of protein fluorophores with appropriate spectral properties has made it possible to employ fluorescence resonance energy transfer (FRET) to assess interactions between three proteins microscopically. Flow cytometry offers excellent sensitivity, effective signal separation and the capacity to assess a large number of events, and, therefore,(More)
BACKGROUND A number of fluorescent caspase substrates and FRET-based indicators have been developed to study the in vivo activation of caspases, a conserved family of proteases critical in inflammatory, and apoptosis signaling pathways. To date, all substrates have measured only one caspase activity. Here, we describe a FRET-based probe for simultaneously(More)
To study the roles of the V3 hypervariable region (amino acid residues 301-336) of the HIV-1 envelope glycoprotein (gp160) during infection, we constructed recombinant vaccinia viruses that expressed either wild-type gp160 (v-env10) or mutant gp160 in which the V3 region was deleted (v-dl29.1 and v-dl29.2). In v-dl29.1 the V3 loop, formed by disulfide(More)
We report a physical and functional association between the Tec-family tyrosine kinase Itk (Emt/Tsk) and the nuclear import chaperone karyopherin alpha (Rch1alpha) in human T cells. The Itk-SH3 domain and the Rch1alpha proline-rich (PR) motif were crucial for the Itk/Rch1alpha constitutive interaction as demonstrated by directed mutagenesis of the Rch1alpha(More)
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