MAMMALIAN RNA-DEPENDENT DEAMINASES AND EDITED MESSENGER-RNAS

The past year has witnessed major progress in the field of mammalian n uclear RNA editing. Two new sequence-related RNA-dependent adenosine d eaminases, distantly related to the previously characterized double-st randed RNA adenosine deaminase DRADA/dsRAD, have been molecularly char acterized. One of these deaminases edits in vitro with precision for t he molecular determinant that controls the Ca2+ permeability of fast s ynaptic glutamate-gated cation channels. This deaminase, like DRADA, i s expressed in many tissues and the search is now on for more substrat es of these RNA-editing enzymes. Moreover, the physiological role of t he apolipoprotein B RNA editing enzyme APOBEC-1 has been investigated in genetically manipulated mice.