Distribution of transmembrane and globular regions in the proteomes. (A) Fractions of globular and nonglobular parts in membrane proteins. Globular denotes globular domains in nontransmembrane proteins, TM/Globular are globular regions within transmembrane helix containing proteins, TM/Loop are short loops in transmembrane proteins, and TM are the actual transmembrane helices. (B) Ratio of globular regions to transmembrane regions in membrane sequences classified according to the number of transmembrane regions. The diagram only shows ratios for which at least nine transmembrane proteins were found.