Principles of PAR polarity in Caenorhabditis elegans embryos.

A hallmark of cell polarity in metazoans is the distribution of partitioning defective (PAR) proteins into two domains on the membrane. Domain boundaries are set by the collective integration of mechanical, biochemical and biophysical signals, and the resulting PAR domains define areas of cytosol specialization. However, the complexity of the signals acting on PAR proteins has been a barrier to uncovering the general principles of PAR polarity. We propose that physical studies, when combined with genetic data, provide new understanding of the mechanisms of polarity establishment in the Caenorhabditis elegans embryo and other organisms.