Towards the application of Tc toxins as a universal protein translocation system

Using a combination of electron microscopy, X-ray crystallography and in vitro translocation assays the Raunser group demonstrated that it is possible to turn Tc toxins into customizable molecular syringes for delivering proteins of interest across membranes.  The requirements for cargo to be successfully delivered are: 

1) Size: 20 - 35 kDa
2) Charge: pI ⋝ 8
3) No highly stable structural elements
4)No amphipathic helices