RNA EDITING - HOW A MESSAGE IS CHANGED

Considerable progress has been made in unraveling the mechanistic feat ures of RNA editing processes in a number of genetic systems. Recent h ighlights include the identification of the catalytic subunit of the m ammalian apolipoprotein B mRNA editing enzyme as a zinc-dependent cyti dine deaminase that binds to RNA, the demonstration that adenosines in brain glutamate receptor pre-mRNAs are converted into inosines and th at double-stranded RNA A deamaminase (dsRAD), the candidate enzyme, is another zinc-dependent RNA nucleotide deaminase, and a mounting body of evidence for a cleavage-ligation mechanism for U insertion/deletion editing in kinetoplastid protozoa.