Two-Dimensional Crystallization of Biological Macromolecules - Molecules: Nucleation, Aggregation and Crystallization - page 109

different membrane proteins may form complexes which are necessary for
natural activity and these may form co-crystals that can be analyzed to
determine protein-protein interactions.
In order to understand more about one specific or a group of mem-
brane proteins it can be worthwhile because of preserved functional com-
petence as described above, to perform structural studies using 2D
crystals and cryoEM. In many cases X-ray and electron crystallography
can provide complementary information. Some of the initial bottlenecks
of a structural study such as expression, purification, stability, and so on
are common to the two techniques. Thus, working together gaining expe-
rience of the properties of a protein will be an advantage.
Summary
For structural biology applications, 2D crystallization together with
cryoEM present an interesting alternative in particular in cases where a
system resembling the natural state is needed. However, inducing 2D
crystals may not only be of interest in structural biology. Biotechnology
applications can be envisaged that profit from an extreme concentration of
proteins which are capable of performing functions such as transport of
signals, ions or small molecules, receptors functioning as specific detec-
tors, etc. (Birge et al ., 1999; Hillebrecht, 2004). Even non-biological appli-
cations have been developed. For example, 2D crystallization of ferritin
has recently been used for fabrication of floating nanodot gate memories
(Miura et al ., 2007), having advantages such as low power consumption,
high operation speed and with possibilities to scale down the dimensions
of memory cells.
Acknowledgments
This work is partially supported by grants from the Swedish Research
Council, EU Network of Excellence “3DEM”, and VINNOVA (Swedish
Governmental Agency for Innovation Systems) program for Multidisciplinary-
Bio as bilateral cooperation with Japan.