Figure 3.
Panel A illustrates classification of exoplasmic inter-transmembrane-domain loops in multipass membrane proteins according to loop length, highlighting prevalence of short loops and rarity of long loops between or downstream of transmembrane domains. The x-axis represents loop length categories (less than or equal to 50, 51-100, greater than 100), and the y-axis represents the count of loops. The chart shows counts and percentages for all outside inter-TMD loops, outside loops between TMD1 and TMD2, and outside loops downstream of TMD2. Panel B presents schematic representations summarizing loop-length prevalence in multipass membrane proteins, demonstrating that proteins without long loops are common, whereas long exoplasmic or cytosolic loops occur infrequently.
Prevalence of short and long inter-TMD loops in multipass proteins. (A) Classification of all exoplasmic inter-TMD loops in multipass proteins by length. Counts and percentages are shown for all outside (exoplasmic) inter-TMD loops, outside loops between TMD1 and TMD2, and outside loops downstream of TMD2. (B) Summary of loop length prevalence in multipass proteins. Most multipass proteins do not contain any long outside or inside loops. Percentages of first outside loops, downstream outside loops, and cytosolic loops that exceed 100 aa are indicated.