Atlanta G. Cook

The Collaborative Computational Project No. 4 (CCP4) is a UK-led international collective with a mission to develop, test, distribute and promote software for macromolecular crystallography. The CCP4 suite is a multiplatform collection of programs brought together by familiar execution routines, a set of common libraries and graphical interfaces. The CCP4 suite has experienced several considerable changes since its last reference article, involving new infrastructure, original programs and graphical interfaces. This article, which is intended as a general literature citation for the use of the CCP4 software suite in structure determination, will guide the reader through such transformations, offering a general overview of the new features and outlining future developments. As such, it aims to highlight the individual programs that comprise the suite and to provide the latest references to them for perusal by crystallographers around the world.

In eukaryotic cells, segregation of DNA replication and RNA biogenesis in the nucleus and protein synthesis in the cytoplasm poses the requirement of transporting thousands of macromolecules between the two cellular compartments. Transport between nucleus and cytoplasm is mediated by soluble receptors that recognize specific cargoes and carry them through the nuclear pore complex (NPC), the sole gateway between the two compartments at interphase. Nucleocytoplasmic transport is specific not only in terms of cargo recognition, but also in terms of directionality, with nuclear proteins imported into the nucleus and RNAs exported from it. How is directionality achieved? How can the receptors be both specific and versatile in recognizing a multitude of cargoes? And how can their interaction with NPCs allow fast translocation? We describe the molecular mechanisms underlying nucleocytoplasmic transport as they have been revealed by structural studies of the receptors and regulators in different steps of transport cycles.