title: An amphipathic polypeptide derived from poly-γ-glutamic acid for the stabilization of membrane proteins.
abstract: Difficulties in the extraction of membrane proteins from cell membrane and their solubilization in native conformations have hindered their structural and biochemical analysis. To overcome these difficulties, an amphipathic polypeptide was synthesized by the conjugation of octyl and glucosyl groups to the carboxyl groups of poly-γ-glutamic acid (PGA). This polymer, called amphipathic PGA (APG), self-assembles as mono-disperse oligomers consisted of 4-5 monomers. APG shows significantly low value of critical micelle concentration and stabilization activity toward membrane proteins. Most of the sodium dodecyl sulfate (SDS)-solubilized membrane proteins from Escherichia coli remain soluble state in the presence of APG even after the removal of SDS. In addition, APG stabilizes purified 7 transmembrane proteins such as bacteriorhodopsin and human endothelin receptor Type A (ETA ) in their active conformations. Furthermore, ETA in complex with APG is readily inserted into liposomes without disrupting the integrity of liposomes. These properties of APG can be applied to overcome the difficulties in the stabilization and reconstitution of membrane proteins.
authors.affiliation: Department of Chemistry, Kookmin University, Seongbuk-gu, Seoul, 136-702, Republic of Korea.
authors.forename: Seong-Gu
authors.initials: SG
authors.lastname: Han
authors.forename: Jung-Hyun
authors.initials: JH
authors.lastname: Na
authors.forename: Won-Kyu
authors.initials: WK
authors.lastname: Lee
authors.forename: Dongkook
authors.initials: D
authors.lastname: Park
authors.forename: Jihye
authors.initials: J
authors.lastname: Oh
authors.forename: Sung-Ho
authors.initials: SH
authors.lastname: Yoon
authors.forename: Cheng-Kang
authors.initials: CK
authors.lastname: Lee
authors.forename: Moon-Hee
authors.initials: MH
authors.lastname: Sung
authors.forename: Yeon-Kyun
authors.initials: YK
authors.lastname: Shin
authors.forename: Yeon Gyu
authors.initials: YG
authors.lastname: Yu
mesh_terms: D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D055550:Protein Stability; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D012995:Solubility; D013501:Surface-Active Agents / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D008565:Membrane Proteins; D013501:Surface-Active Agents; C511775:poly(gamma-glutamic acid); D011099:Polyglutamic Acid; D012967:Sodium Dodecyl Sulfate
keywords: G protein-coupled receptors; detergent; liposomes; membrane isolation; membrane proteins; membrane reconstitution; plasma membrane