Nanopores have emerged as a powerful tool for the analysis of single molecules in solution. The ionic current passed through them is disrupted by analytes in a characteristic and measurable way. Protein nanopores offer high reproducibility in pore dimensions and the ability to introduce site-specific chemical modifications. This has led to the use of these systems as a platform for the study of chemical reactions at the single-molecule level and as an approach towards ultra-fast and cheap sequencing of DNA.

Here I will describe a nanopore system that allows tracking protein co-translocational unfolding at the single-molecule level. Several biological processes require protein translocation through narrow pores. For example, the traffic of proteins across membranes is frequently mediated by them. Furthermore, the proteasome along with chaperones from the AAA+ family unfold proteins by pulling them through a narrow pore. Our single-molecule measurements give insight on how proteins unfold through pores and refold after translocation.

Protein function, on the other hand, is often regulated by chemical modifications of specific residues (i.e. post-translational modifications). Based on the ability of nanopores to detect sequence features I will show that single-molecule and site-specific detection of post-translational modifications is feasible.