The five most proximal C-terminal (C-term.) amino acids and the five first amino acids from the predicted mature N terminus (N term.) are presented for α4 and β2 subunits along with the specific linker sequences introduced during concatenation. C-terminal tail lengths were obtained from NCBI (SwissProt accession nos. P43681 for α4 and P17787 for β2), whereas N-terminal lengths were derived from the definition of an α-helical hydrophobic leucine anchor as described in the Results. For tetrameric and pentameric constructs, numbers indicate the construct position of each subunit (e.g., α²: α4 subunit in the second construct position).