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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.