Fig. 1

Negatively charged amino acids are amongst the rarest residues in TMHs and ±5 flanking residues. Bar charts of the abundance of each amino acid type in the TMHs with flank lengths of the accompanying ±5 residues from the (a) UniHuman single-pass proteins, (b) ExpAll single-pass proteins, (c) UniHuman multi-pass proteins, and (d) ExpAll multi-pass proteins. Amino acid types on the horizontal axis are listed in descending count. The bars were coloured according to categorisations of hydrophobic, neutral and hydrophilic types according to the free energy of insertion biological scale [36]. Grey represents hydrophilic amino acids that were found to have a positive ΔG _app, and blue represents hydrophobic residues with a negative ΔG _app, purple denotes negative residues and positive residues are coloured in orange. The abundances of key residues are labelled