D, the BMY 7378 existence of oligomers h Higher order ABCG2 in both isolated membranes and whole cell preparations. In addition was labeled using fluorescence energy transfer analysis of GFP-resonance / YFP ABCG2 in intact cells, Wang et al. Also showed the existence of oligomeric ABCG2 although the exact size E of the complex are not assessed by this method. Sp Ter, through the investigation of human ABCG2 revealed by cryo-electron microscopy that purified human ABCG2 may exist as a homo-octamer composed of four homo-dimer ABCG2 complex. But in another study using the cleaning method of improving the lipid environment, it was found that purified ABCG2 in the presence of solubilized membrane components, a tetrameric complex when expressed in Sf9 cells.
Cleaned in a third study by electron microscopy of ABCG2 was also found that the big e oligomeric complex is a tetramer of ABCG2. Although the causes for the gap between the three following investigations purified ABCG2 are not known, it is clear that all these studies have demonstrated the existence of an oligomeric complex ABCG2 gr Tivozanib He entered as a dimer. However, the use of detergents, and various methods of cleaning in these studies influence the outcome at least as stable ABCG2 complex is a tetramer, and manipulation of various chemical or physical forces Kr Break the h Higher forms oligomers from tetramers. The observation of tetramers in two of three studies of purified ABCG2 is compatible with this conclusion. By mapping L Or between ions and Co-Immunpr Zipitation of differentially tagged constructs ABCG2, Xu et al.
mapped the oligomerization Cathedral ne of the human ABCG2 its TMS consisting of extracellular Ren loop 3 and its flanking TM segments. The polypeptide consisting of TM5 TM6 ECL3 not only a homopolymer byitself is dodecameric complex, but also has a dominant negative effect on the transport function of ABCG2 wild-type drugs, possibly by forming complexes with straight wild-type molecule. We have found that ECL3, TM5 and TM6 contain all the oligomerization activity of t, suggesting that each of these segments k Can for three different intermolecular contacts for the formation of a homododecamer. However, each segment plays a role Function in the various ABCG2 drug traffic. W While TM5 is essential for ABCG2 function in the transport of drugs, are replaced TM6 and ECL3 Ables.
ECL3 is an interesting loop containing three cysteine residues, which can be connected to the formation of intra-and intermolecular disulfide bonds k. W While Cys603 was found there the intermolecular disulfide bond form, and can m act resembled enough, to form dimers, as indicated, with non-reducing PAGE, the formation of the oligomeric ABCG2 causes not dependent on intermolecular disulfide bonds nts. Furthermore, it is that t Cys603 ben not the expression or localization of ABCG2 To do prior to ATPase activity is not t or ABCG2 transport is essential. In view of the M Possibility that the intermolecular disulfide oxidation may need during the sample preparation, the above studies suggest that functional ABCG2 does not necessarily require an intermolecular disulfide bond for its function and / or oligomerization. Regulation of ABCG2 expression in normal human TISS