GUIDE RNA-INDEPENDENT AND GUIDE RNA-DEPENDENT URIDINE INSERTION INTO CYTOCHROME-B MESSENGER-RNA IN A MITOCHONDRIAL LYSATE FROM LEISHMANIA-TARENTOLAE - ROLE OF RNA SECONDARY STRUCTURE

A primer extension assay was used for the detection of uridine inserti ons occurring in vitro in synthetic preedited cytochrome b mRNA during incubation with a Leishmania tarentolae mitochondrial extract. Two di fferent activities were detected that inserted uridines within the fir st two editing sites: one that is dependent on the secondary structure of the mRNA but is independent of both exogenous and endogenous guide RNA, and a second that does not put the same structural constraints o n the mRNA, but is dependent on the presence of a cognate guide RNA.