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Every RNA polymerase II transcript receives a 5′-end 7-methylguanosine (m7G) cap, which is rapidly bound by the nuclear cap–binding complex (CBC). Two recent studies now reveal that the CBC associates with a variety of effector proteins that enable it to interrogate nascent RNA, discriminating between distinct RNA subclasses and routing them either toward distinct maturation pathways or toward decay. Thus, the CBC has an early role in policing cellular RNA.
DNA replication begins with prereplication-complex formation at origins and is followed by helicase activation to unwind DNA at the replication fork. This Perspective compares bacterial DnaB and eukaryotic MCM2–7 helicase-loading mechanisms and discusses emerging data supporting current models of how two MCM2–7 complexes are loaded to form a double hexamer.
