Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 5QY, UK.
J Mol Biol. 2012 Oct 12;423(1):1-13. doi: 10.1016/j.jmb.2012.06.033. Epub 2012 Jun 28.
That membrane protein complexes could survive in the gas phase had always seemed impossible. The lack of chargeable residues, high hydrophobicity, and poor solubility and the vast excess of detergent contributed to the view that it would not be possible to obtain mass spectra of intact membrane complexes. With the recent success in recording mass spectra of these complexes, first from recombinant sources and later from the cellular environment, many surprising properties of these gas phase membrane complexes have been revealed. The first of these was that the interactions between membrane and soluble subunits could survive in vacuum, without detergent molecules adhering to the complex. The second unexpected feature was that their hydrophobicity and, consequently, lower charge state did not preclude ionization. The final surprising finding was that these gas phase membrane complexes carry with them lipids, bound specifically in subunit interfaces. This provides us with an opportunity to distinguish annular lipids that surround the membrane complexes, from structural lipids that have a role in maintaining structure and subunit interactions. In this perspective, we track these developments and suggest explanations for the various discoveries made during this research.
一直以来,人们都认为膜蛋白复合物不可能在气相中存在。由于缺乏可带电荷的残基、高度疏水性、较差的溶解性以及大量去污剂的存在,人们普遍认为不可能获得完整膜复合物的质谱。然而,最近在从重组来源到细胞环境的膜复合物的质谱记录方面取得了成功,揭示了这些气相膜复合物的许多令人惊讶的特性。首先,膜和可溶性亚基之间的相互作用可以在真空中存在,而无需去污剂分子附着在复合物上。其次,出乎意料的是,它们的疏水性以及由此导致的较低电荷状态并不会妨碍离子化。最后一个令人惊讶的发现是,这些气相膜复合物带有特定结合在亚基界面上的脂质。这为我们提供了一个机会,可以区分环绕膜复合物的环形脂质与在维持结构和亚基相互作用中发挥作用的结构脂质。在本文中,我们跟踪了这些发展,并对在这项研究中做出的各种发现提出了一些解释。