Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
Recent work has clarified how higher eukaryotic cells 'licence' DNA replication precisely once per cycle. An inhibitor, geminin, prevents replication before mitosis by inhibiting the replication factor Cdt1. Degradation of geminin in anaphase allows Cdt1 to promote binding of MCM proteins, and hence DNA replication.
Molecular chaperones have long been heralded as machines for folding and salvaging proteins. However, not every attempt to fold or refold a protein can be successful. Chaperones are known to participate in the degradation of misfolded polypeptides, but a direct link between folding and degradation pathways has remained elusive. Two recent reports show that the co-chaperone CHIP mediates ubiquitin-dependent degradation of substrates bound to heat-shock protein 70 (Hsp70) and/or Hsp90.
Chemokines are generally appreciated within the realm of immunology as chemoattractant cytokines that are involved in constitutive and inducible movement of white blood cells. However, evidence increasingly points to a broader function of chemokines in cellular and developmental biology, and the initially T-associated chemokine RANTES has now been shown to produce age-dependent effects on developing human astrocytes.
Members of the Bcl-2 family are critical regulators of apoptosis and have become attractive targets for the development of anti-cancer drugs. The latest discovery of small-molecule inhibitors of Bcl-2 proteins may provide the sought-after leads for the development of new anti-cancer therapy
Nitric oxide regulates a broad functional spectrum of proteins by S-nitrosylation. Specificity is conferred by acid–base and hydrophobic motifs that target critical cysteine residues and by protein–protein interactions that confine the signals in space.
Myosin II regulatory light chains have an important role in the organization and function of the contractile machinery at cytokinesis. Two recent reports provide new insights into these important proteins.
Loss of sister-chromatid cohesion triggers chromosome segregation. Several recent reports show that the protease Esp1 cleaves the cohesin subunit Scc1/Mcd1 to induce sister-chromatid segregation in yeast and vertebrates. This finding indicates that cohesin cleavage may control sister-chromatid separation in all eukaryotes.
Recent work has revealed an evolutionarily conserved trio of proteins that regulate cell polarity in epithelial cells, embryonic blastomeres and neural precursors. This common cell-polarity mechanism is used in cell-specific ways, as highlighted by the recent finding that at least two different types of asymmetric division are observed in Drosophila neural precursors.
