Crystallization and preliminary X-ray crystallographic studies of transglutaminase 2 in complex with Ca2+

Transglutaminase 2 (TG2) is a multi-functional protein that has been implicated in a variety of physiological cellular activities, including apoptosis, angiogenesis and cellular differentiation. Two functions of TG2 are protein cross-linking and GTP hydrolysis activities. The protein cross-linking activity of TG2 is positively controlled by calcium; however, the molecular mechanism of its Ca2+-dependent activity is completely unknown. In the present study, full-length human TG2 in complex with Ca2+ was overexpressed, purified and crystallized at 20 degrees C as a first step towards elucidating this mechanism. X-ray diffraction data were collected to a resolution of 3.4 angstrom from a crystal belonging to space group C222(1), with unit-cell parameters a = 133.08, b = 216.30, c = 166.26 angstrom. Based on these data, the asymmetric unit was estimated to contain three molecules.