Amino Acids: Research Results from University of Houston Update Understanding of Amino Acids

Investigators publish new data in the report "Self-association of models of transmembrane domains of ErbB receptors in a lipid bilayer." According to the authors of recent research published in the Biophysical Journal, "Association of transmembrane ? helices is facilitated by the close packing of small residues present along the amino-acid sequence. Extensive studies have established the role of such small residue motifs (GxxxG) in the dimerization of Glycophorin A (GpA) and helped to elucidate the association of TM domains in the epidermal growth factor family of receptors (ErbBs)."

"Although membrane-mediated interactions are known to contribute under certain conditions to the dimerization of proteins, their effect is often considered nonspecific, and any potential dependence on protein sequence has not been thoroughly investigated. We recently reported that the association of GpA is significantly assisted by membrane-induced contributions as quantified in different lipid bilayers. Herein we extend our studies to explore the origin of these effects and quantify their magnitude using different amino-acid sequences in the same lipid environment. Using a coarse-grained model that accounts for amino-acid specificity, we perform extensive parallel Monte Carlo simulations of ErbB homodimerization in dipalmitoyl-phosphatidylcholine lipid bilayers. A detailed characterization of dimer formation and estimates of the free energy of association reveal that the TM domains show a significant affinity to self-associate in lipid bilayers, in qualitative agreement with experimental findings. The presence of GxxxG motifs enhances favorable protein-protein interactions at short separations. However, the lipid-induced attraction presents a more complex character than anticipated," wrote A. Prakash and colleagues, University of Houston.

The researchers concluded: "Depending on the interfacial residues, lipid-entropic contributions support a decrease of separation or a parallel orientation to the membrane normal, with important implications for protein function."

Prakash and colleagues published their study in Biophysical Journal (Self-association of models of transmembrane domains of ErbB receptors in a lipid bilayer. Biophysical Journal, 2010;99(11):3657-65).

For additional information, contact A. Prakash, Dept. of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas, United States.

Keywords: City:Houston, State:Texas, Country:United States, Region:North and Central America, Peptides, Amino Acids.

This article was prepared by NewsRx editors from staff and other reports. Copyright 2011, NewsRx.com.

Source: http://c.moreover.com/click/here.pl?r5685937136&f=378

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