LZR mutants of v-Myb exhibit elevated transcriptional activity and transform erythroid cells.

Schematic representation of full-length wild-type v-Myb protein with DNA-binding domain (DBD), transactivation domain (TA), and leucine zipper region (LZR). The specific deletion mutations in v-Myb C-terminus are delimited by dotted lines and characterized by the numbers of the first and last deleted amino acid. In the ΔC mutant, C-terminal amino acids were deleted; ΔLZ1, ΔLZ2, ΔP1, ΔP2, and ΔP3 mutants carry internal in-frame deletions as indicated. In the point mutant L3,4A, leucines (L) 325 and 332 were replaced by alanine (A). The transactivation activity of Myb proteins was determined by the standard CAT assay in transiently transfected fibroblasts. Results are representative of 2 independent experiments. Assays were performed in triplicate. The transformation potential of various Myb mutants for myeloid and erythroid cells (myelo and ery, respectively) is shown. Transform indicates transforming potential; transact, transactivation activity.