Method of nanopore sequencing

A method of characterising a target analyte, comprising:

• (a) contacting the analyte with a hetero-oligomeric transmembrane pore such that the target analyte moves through the pore, wherein the pore comprises a first monomer and a second monomer at a specific stoichiometric ratio in the range of 1:13 to 13:1 and wherein the specific stoichiometric ratio is not 1:1, wherein the first monomer is different from the second monomer, and wherein:
• (i) the first monomer comprises SEQ ID NO:
• 2, or 32 while the second monomer comprises a variant of SEQ ID NO:
• 2, or the first monomer comprises a variant of SEQ ID NO:
• 2 while the second monomer comprises SEQ ID NO:
• 2;
• or
• (ii) the first monomer comprises SEQ ID NO:
• 32 while the second monomer comprises a variant of SEQ ID NO:
• 32, or the first monomer comprises a variant of SEQ ID NO:
• 32 while the second monomer comprises SEQ ID NO:
• 32;
• and
• (b) taking one or more measurements as the target analyte moves with respect to the pore, wherein the measurements are indicative of one or more characteristics of the target analyte, and thereby characterising the target analyte.