Method of characterising a target polypeptide using a nanopore

A method of controlling movement of a target polypeptide through a transmembrane protein pore, the method comprising:

• (i) conjugating the target polypeptide to a polynucleotide to form a polynucleotide-polypeptide conjugate;
• (ii) contacting the polynucleotide-polypeptide conjugate with a polynucleotide-handling protein;
• (iii) controlling the movement of the polynucleotide through the transmembrane protein pore using the polynucleotide-handling protein, thereby controlling the movement of the target polypeptide through the transmembrane protein pore;
• and
• (iv) taking one or more electrical measurements as the polynucleotide-polypeptide conjugate moves with respect to the transmembrane protein pore.
• wherein the polynucleotide-polypeptide conjugate comprises a leader that facilitates threading of the polynucleotide-polypeptide conjugate through the transmembrane protein pore, and
• wherein the transmembrane protein pore comprises a cis side and a trans side.