RNA Transcription's Newfound Complexity

Expression of specific genes is controlled by the complex pattern of phosphorylation of the enzyme that converts DNA into RNA, according to a report by Dirk Eick of the Munich Center for Integrated Protein Science, Shona Murphy of the University of Oxford, and colleagues in Science (2007, 318, 1777 and 1780). The enzyme, RNA polymerase II, is attached via an "umbilical cord" to proteins that help process the RNA product. This flexible tether, known as the carboxyl-terminal domain (CTD), is made of repeated sequences of amino acids. The phosphorylation pattern of these amino acids "has been proposed as a code that controls the binding of different regulatory factors to the enzyme," explains Jeffry L. Corden of Johns Hopkins Medical School in an accompanying Science commentary. The researchers show that CTD can be phosphorylated at more sites than previously thought "and link, for the first time, expression of specific genes with a distinct CTD phosphorylation pattern," Corden writes.