MKL/Myocardin Like Protein 2 (MKL2)

MKL2 was a strong transactivator of promoters containing serum response elements (SRE). Activation by MKL2 had a threshold effect in that 0.5 microgram caused little activation, whereas 2.0 microgram caused 40-fold activation. Gel mobility shift assays indicated that MKL2 did not bind DNA by itself, but formed a complex with SRF. Mutation analysis indicated that the N-terminal 71 amino acids of MKL2 repressed the interaction between MKL2 and SRF. The leucine zipper-like domain of MKL2 promoted interaction with itself and with MKL1, as well as contributed to transactivation. The transcriptional activation domain of MKL2 was mapped to the C terminus, and the region from amino acid 701 to the C terminus showed higher transcriptional activity than the full-length protein.