The Journal of Cell Biology Mini-Review

Nanotubes, exosomes, and nucleic acid-binding peptides provide novel mechanisms of intercellular communication in eukaryotic cells: implications in health and disease

Belting, M., Wittrup, A. — 2008-12-29

The prevailing view that eukaryotic cells are restrained from intercellular exchange of genetic information has been challenged by recent reports on nanotubes, exosomes, apoptotic bodies, and nucleic acid–binding peptides that provide novel pathways for cell–cell communication, with implications in health and disease.

The Mad2 partial unfolding model: regulating mitosis through Mad2 conformational switching

Skinner, J. J., Wood, S., Shorter, J., Englander, S. W., Black, B. E. — 2008-12-01

The metamorphic Mad2 protein acts as a molecular switch in the checkpoint mechanism that monitors proper chromosome attachment to spindle microtubules during cell division. The remarkably slow spontaneous rate of Mad2 switching between its checkpoint inactive and active forms is catalyzed onto a physiologically relevant time scale by a self–self interaction between its two forms, culminating in a large pool of active Mad2. Recent structural, biochemical, and cell biological advances suggest that the catalyzed conversion of Mad2 requires a major structural rearrangement that transits through a partially unfolded intermediate.

Cytoplasmic diffusion: molecular motors mix it up

Brangwynne, C. P., Koenderink, G. H., MacKintosh, F. C., Weitz, D. A. — 2008-11-17

Random motion within the cytoplasm gives rise to molecular diffusion; this motion is essential to many biological processes. However, in addition to thermal Brownian motion, the cytoplasm also undergoes constant agitation caused by the activity of molecular motors and other nonequilibrium cellular processes. Here, we discuss recent work that suggests this activity can give rise to cytoplasmic motion that has the appearance of diffusion but is significantly enhanced in its magnitude and which can play an important biological role, particularly in cytoskeletal assembly.