7SK RNA

7SK was discovered as an abundant small nuclear RNA in the mid-70s but a possible function has only recently been suggested. Two independent studies have found that 7SK RNA binds the CDK9/cyclin T complex (known as elongation factor P-TEFb). P-TEFb activates transcription by phosphorylating the C-terminal domain of RNA polymerase II. This process is negatively regulated by the 7SK RNP. The secondary structure of 7SK RNA shown here was proposed by Wasserman and Steitz on the basis of chemical modification and enzymatic cleavage experiments. This family contains a number of pseudogenes and 7SK derived repeats.