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Crystal Structure of the Glycophorin A Transmembrane Dimer in Lipidic Cubic Phase
Structural highlights
FunctionGLPA_HUMAN Glycophorin A is the major intrinsic membrane protein of the erythrocyte. The N-terminal glycosylated segment, which lies outside the erythrocyte membrane, has MN blood group receptors. Appears to be important for the function of SLC4A1 and is required for high activity of SLC4A1. May be involved in translocation of SLC4A1 to the plasma membrane. Is a receptor for influenza virus. Is a receptor for Plasmodium falciparum erythrocyte-binding antigen 175 (EBA-175); binding of EBA-175 is dependent on sialic acid residues of the O-linked glycans. Appears to be a receptor for Hepatitis A virus (HAV).[1] [2] [3] [4] [5] [6] Publication Abstract from PubMedThe mechanisms of assembly and function for many important type I/II (single-pass) transmembrane (TM) receptors are proposed to involve the formation and/or alteration of specific interfaces among their membrane-embedded alpha-helical TM domains. The application of lipidic cubic phase (LCP) bilayer media for crystallization of single-alpha-helical TM complexes has the potential to provide valuable structural and mechanistic insights into many such systems. However, the fidelity of the interfaces observed in crowded crystalline arrays has been difficult to establish from the very limited number of such structures determined using X-ray diffraction data. Here we examine this issue using the glycophorin A (GpA) model system, whose homodimeric TM helix interface has been characterized by solution and solid-state NMR and biochemical techniques but never crystallographically. We report that a GpA-TM peptide readily crystallized in a monoolein cubic phase bilayer, yielding a dimeric alpha-helical structure that is in excellent agreement with previously reported NMR measurements made in several different types of host media. These results provide compelling support for the wider application of LCP techniques to enable X-ray crystallographic analysis of single-pass TM interactions. Crystal Structure of the Glycophorin A Transmembrane Dimer in Lipidic Cubic Phase.,Trenker R, Call ME, Call MJ J Am Chem Soc. 2015 Dec 10. PMID:26642914[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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