Open AccessCrystallization and preliminary X‐ray analysis of pseudo‐merohedrally twinned crystals of the full‐length β 2 subunit of the Kv1 K + channel from Rattus norvegicus
Author(s) -
Shimamura Tatsuro,
Shamotienko Oleg,
Akhtar Sobia,
Dolly J. Oliver,
Iwata So
Publication year - 2004
Publication title -
acta crystallographica section d
Language(s) - English
Resource type - Journals
ISSN - 1399-0047
DOI - 10.1107/s0907444904004536
Subject(s) - protein subunit , crystallography , crystallization , molecular replacement , resolution (logic) , crystal (programming language) , crystal structure , group (periodic table) , crystal twinning , space group , chemistry , x ray crystallography , physics , optics , diffraction , microstructure , biochemistry , gene , computer science , programming language , organic chemistry , artificial intelligence
The eukaryotic Kv1 voltage‐gated K + channel is composed of four α subunits and four β subunits. The full‐length β 2 subunit from Rattus norvegicus has been expressed in Esherichia coli , purified and then crystallized. A careful molecular‐replacement study using the structure of the truncated β 2 subunit reveals that the crystals are perfectly pseudo‐merohedrally twinned. While the apparent space group of the crystals was P 42 1 2, the real space group was shown to be P 2 1 2 1 2, with unit‐cell parameters a = 222.6, b = 222.6, c = 82.3 Å. An asymmetric unit of the crystal contains two β 2 tetramers (MW = 340 kDa). A data set was collected from a crystal to 2.0 Å resolution, with 266 659 independent observations (93.0% complete) and R merge = 0.06. Although the crystals are perfectly twinned, they are still suitable for structural determination by molecular replacement using the truncated β 2 ‐subunit structure.