Measuring editing activity and identifying cytidine-to-uridine mRNA editing factors in cells and biochemical isolates.

Cytidine deaminases with the capacity to act on nucleic acids play a critical role in regulating the proteome through diversification of expressed sequence beyond that encoded in the genome. A family of these enzymes, known as the APOBEC family of cytidine deaminases, has been identified in mammalian cells. APOBEC-1 edits messenger RNA, whereas other family members affect mRNA coding capacity by editing single-stranded DNA in expressed regions of the genomes. Biochemical isolation and analysis of APOBEC proteins and their interacting factors have led to an understanding of the diverse cellular processes including lipoprotein metabolism, antibody production, viral infectivity, and cancer. Practical approaches will be described for the measurement of editing activity and the analysis of proteins involved in C-to-U and dC-to-dU editing.