Volume 5 Issue 11, November 2003

The most interesting discoveries are often those that couple distinct fields of science in unexpected ways. The marriage of the nuclear pore complex to the kinetochore and spindle checkpoint regulation is a recent example, raising the question of why such divergent processes as mitosis and nuclear transport use common proteins.

During organogenesis different cells must recognize and adhere to each other in a complicated orchestration of cell movements that requires intricate regulation of cell adhesions. A Maf transcription factor, Traffic jam, has been found to regulate a panel of cell adhesion molecules, and the interactions between germ cells and somatic cells to shape the mature gonad.

The choice of ubiquitination substrates of Cul1- and Cul2-based E3 ubiquitin protein ligase complexes is dictated by the identity of their substrate-specific adaptors, known as F-box and BC-box proteins, respectively. Recent work suggests that members of the large family of BTB-domain proteins define a new class of substrate-specific adaptors of Cul3-based E3 complexes. This finding places many signalling pathways in which BTB-domain proteins participate under direct control of the ubiquitination pathway.

Bone-marrow-derived stem cells have been shown to contribute to Purkinje neurons in the cerebellum of adult humans and mice. A new study identifies cell fusion as the mechanism underlying this phenomenon, and shows that the bone marrow cell portion of the resulting binucleate heterokaryons acquires the morphological and molecular characteristics of Purkinje neurons over time.

Rab GTPases function at all stages of the endocytic and exocytic pathways. Although it is clear that each Rab is required for specific transport events, the process by which they are recruited to distinct compartments along the membrane trafficking pathway has remained obscure. Recent data suggests that a member of the Yip family is important for the membrane recruitment of endosomal Rabs.