Two forms of activation-induced cytidine deaminase differing in their ability to bind agarose.

BACKGROUND

Activation-induced cytidine deaminase (AID) is a B-cell-specific DNA mutator that plays a key role in the formation of the secondary antibody repertoire in germinal center B cells. In the search for binding partners, protein coimmunoprecipitation assays are often performed, generally with agarose beads.

METHODOLOGY/PRINCIPAL FINDINGS: We found that, regardless of whether cell lysates containing exogenous or endogenous AID were examined, one of two mouse AID forms bound to agarose alone.

CONCLUSIONS/SIGNIFICANCE: These binding characteristics may be due to the known post-translational modifications of AID; they may also need to be considered in coimmunoprecipitation experiments to avoid false-positive results.