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Certain pathogens and bacterial toxins exhibit exquisite host specificity, the determinants of which often remain mysterious. A recent report shows that the human specificity of the pore-forming toxin intermedilysin (ILY), a member of the cholesterol-dependent cytolysins (CDCs), is due to its specific interaction with the human cluster of differentiation protein CD59.
Three recent reports identify the roles of specific ribonucleases necessary for efficient termination of transcription by RNA polymerase II. In one case, the primary cleavage event is carried out by a ribozyme encoded in the pre-mRNA itself.