Expression, purification and preliminary NMR characterization of isotopically labeled wild-type human heterotrimeric G protein αi1

► A protocol was developed to prepare pure isotopically labeled human Gαi1 for NMR. ► N-terminally truncated Gαi1 (with unstructured residues removed) was also prepared. ► Success depended on vector choice, low induction temperature and media supplements. ► NMR spectra recorded at 35 °C had better peak definition than at lower temperatures. ► Spectra provided preliminary evidence for widespread intramolecular motions in Gαi1.