title: CW-EPR studies revealed different motional properties and oligomeric states of the integrin β1a transmembrane domain in detergent micelles or liposomes.
abstract: Integrins are heterodimeric membrane proteins that regulate essential processes: cell migration, cell growth, extracellular matrix assembly and tumor metastasis. Each integrin α or β subunit contains a large extracellular domain, a single transmembrane (TM) domain, and a short cytoplasmic tail. The integrin TM domains are important for heterodimeric association and dissociation during the conversion from inactive to active states. Moreover, integrin clustering occurs by homo-oligomeric interactions between the TM helices. Here, the transmembrane and cytoplasmic (TMC) domains of integrin β1a were overexpressed, and the protein was purified in detergent micelles and/or reconstituted in liposomes. To investigate the TM domain conformational properties of integrin β1a, 26 consecutive single cysteine mutants were generated for site-directed spin labeling and continuous-wave electron paramagnetic resonance (CW-EPR) mobility and accessibility analyses. The mobility analysis identified two integrin β1a-TM regions with different motional properties in micelles and a non-continuous integrin β1a-TM helix with high immobility in liposomes. The accessibility analysis verified the TM range (Val737-Lys752) of the integrin β1a-TMC in micelles. Further mobility and accessibility comparisons of the integrin β1a-TMC domains in micelles or liposomes identified distinctively different oligomeric states of integrin β1a-TM, namely a monomer embedded in detergent micelles and leucine-zipper-like homo-oligomeric clusters in liposomes.
authors.affiliation: 1] Hefei National Laboratory of Microscale Physical Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China [2] High Magnetic Field Laboratory, Hefei institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, 230031, P. R. China.
authors.forename: Lu
authors.initials: L
authors.lastname: Yu
authors.affiliation: Hefei National Laboratory of Microscale Physical Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Hefei National Laboratory of Microscale Physical Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China.
authors.forename: Shenglong
authors.initials: S
authors.lastname: Ling
authors.affiliation: High Magnetic Field Laboratory, Hefei institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, 230031, P. R. China.
authors.forename: Sanling
authors.initials: S
authors.lastname: Liu
authors.affiliation: Hefei National Laboratory of Microscale Physical Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China.
authors.forename: Liang
authors.initials: L
authors.lastname: Xiao
authors.affiliation: Hefei National Laboratory of Microscale Physical Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China.
authors.forename: Yanlong
authors.initials: Y
authors.lastname: Xin
authors.affiliation: Hefei National Laboratory of Microscale Physical Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China.
authors.forename: Chaohua
authors.initials: C
authors.lastname: Lai
authors.affiliation: Hefei National Laboratory of Microscale Physical Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Xiong
authors.affiliation: Hefei National Laboratory of Microscale Physical Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China.
authors.forename: Longhua
authors.initials: L
authors.lastname: Zhang
authors.affiliation: 1] Hefei National Laboratory of Microscale Physical Sciences, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China [2] High Magnetic Field Laboratory, Hefei institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, 230031, P. R. China.
authors.forename: Changlin
authors.initials: C
authors.lastname: Tian
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D003902:Detergents / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D019012:Integrin beta1 / Q000737:chemistry* / Q000378:metabolism; D008081:Liposomes / Q000737:chemistry* / Q000378:metabolism; D008823:Micelles; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D003902:Detergents; D019012:Integrin beta1; D008081:Liposomes; D008823:Micelles