Mapping of functional domains within the v-erb A oncogene protein: the remnants of the hormone binding domain play multiple, vital roles in protein action.

The v-erb A oncogene represents a virally-transduced variant of a thyroid hormone receptor. Biochemical characterization of a series of mutant v-erb A proteins demonstrates that nuclear localization and DNA binding are both necessary for v-erb A function in the neoplastic cell and are mediated by multiple, overlapping domains within the v-erb A polypeptide. Domains of the v-erb A protein necessary for sequence-specific and sequence-independent DNA binding are distinguishable from one another, and encompass sequences projecting beyond the zinc-finger motifs themselves. Although unable to bind T3 thyroid hormone, the remnants of the hormone binding domain continue to play unanticipated essential roles in v-erb A protein function.