Disordered regions in transmembrane proteins.
The functions of transmembrane proteins in living cells are widespread; they range from various transport processes to energy production, from cell-cell adhesion to communication. Structurally, they are highly ordered in their membrane-spanning regions, but may contain disordered regions in the cytosolic and extra-cytosolic parts. In this study, we have investigated the disordered regions in transmembrane proteins by a stringent definition of disordered residues on the currently available largest experimental dataset, and show a significant correlation between the spatial distributions of positively charged residues and disordered regions. This finding suggests a new role of disordered regions in transmembrane proteins by providing structural flexibility for stabilizing interactions with negatively charged head groups of the lipid molecules. We also find a preference of structural disorder in the terminal--as opposed to loop--regions in transmembrane proteins, and survey the respective functions involved in recruiting other proteins or mediating allosteric signaling effects. Finally, we critically compare disorder prediction methods on our transmembrane protein set. While there are no major differences between these methods using the usual statistics, such as per residue accuracies, Matthew's correlation coefficients, etc.; substantial differences can be found regarding the spatial distribution of the predicted disordered regions. We conclude that a predictor optimized for transmembrane proteins would be of high value to the field of structural disorder.
Institute of Enzymology, RCNS, HAS, Magyar Tudósok körútja 2, 1117 Budapest, Hungary. Electronic address: tusnady.gabor@ttk.mta.hu.
Gábor E
GE
Tusnády
Institute of Enzymology, RCNS, HAS, Magyar Tudósok körútja 2, 1117 Budapest, Hungary.
László
L
Dobson
Institute of Enzymology, RCNS, HAS, Magyar Tudósok körútja 2, 1117 Budapest, Hungary; VIB Structural Biology Research Center, VUB, Building E, Pleinlaan 2, 1050 Brussels, Belgium.
Peter
P
Tompa
D000595:Amino Acid Sequence; D019295:Computational Biology / Q000379:methods; D030562:Databases, Protein; D020407:Internet; D008565:Membrane Proteins / Q000737:chemistry*; D008958:Models, Molecular; D011487:Protein Conformation; D015203:Reproducibility of Results
D008565:Membrane Proteins
Intrinsically disordered residues; Positive inside rule; Prediction; Topology; Transmembrane protein