YY1 Associated Factor 2 (YAF2)

YY1-associated factor 2 is a protein interacts with YY1, a zinc finger protein involved in negative regulation of muscle-restricted genes. This gene product itself contains a single N-terminal C2-X10-C2 zinc finger, and in contrast to YY1, is up-regulated during myogenic differentiation. It also facilitates proteolytic cleavage of YY1 by the calcium- activated protease, m-calpain, suggesting a mechanism by which this protein antagonizes the negative effect of YY1.YAF2 mRNA increased during the in vitro differentiation of rat skeletal and cardiac muscle cells, in contrast to the downregulation of YY1. Overexpression of YAF2 in mouse myoblast cells stimulated myogenic promoter activity. Cotransfection and expression of YY1 in these cells reversed the stimulatory effect of YAF2.