Protein translocation through anthrax toxin channels formed in planar lipid bilayers.

The 63-kDa fragment of the protective antigen (PA) component of anthrax toxin forms a heptameric channel, (PA63)7, in acidic endosomal membranes that leads to the translocation of edema factor (EF) and lethal factor (LF) to the cytosol. It also forms a channel in planar phospholipid bilayer membranes. What role does this channel play in the translocation of EF and LF? We report that after the 263-residue N-terminal piece of LF (LFN) binds to its receptor on the (PA63)7 channel and its N-terminal end enters the channel at small positive voltages to block it, LFN is translocated through the channel to the opposite side at large positive voltages, thereby unblocking it.

Anthrax protective antigen: efficiency of translocation is independent of the number of ligands bound to the prepore.

Heptameric anthrax protective antigen (termed prepore), which assembles at the mammalian cell surface, competitively binds edema factor (EF) and/or lethal factor (LF). It then transports them to an acidic intracellular compartment and mediates their translocation across the membrane to the cytosol. Steric constraints limit to three the number of molecules of EF and/or LF that can bind simultaneously to prepore.

Resources for targeted insertional and deletional mutagenesis in Arabidopsis.

The maize transposons Activator (Ac) and Dissociation (Ds) are active in many monocots and dicots, including Arabidopsis. We describe a new Ac-derived transposon construct, designated the Ds-loxP T-DNA, which can be used for both insertional and deletional mutagenesis. There are loxP sites in both orientations on both the transposon and the donor site T-DNA and an arrangement of marker genes that permits selection of transposition events, as well as deletions and inversions extending from the donor site to a transposon reinserted on either side of it.

Exchange characteristics of calcium ions bound to anthrax protective antigen.

Protective antigen (PA), the receptor-binding moiety of anthrax toxin, contains two calcium atoms buried within domain 1(') (amino acid residues 168-258). We showed that these ions are stably bound and exchange with free 45Ca(2+) only slowly (t(1/2) approximately 4.0 h).

Multiple factors analysis on liver metastasis from colorectal cancer.

Objective: To investigate the clinical factors related with liver metastasis from colorectal cancer.

Methods: 1 312 colorectal cancer patients treated from 1988 to 1997 were collected to set up the database. Binary and multinomial logistic regression (SPSS 10.