Use of altered specificity mutants to probe a specific protein-protein interaction in differentiation: The GATA-1 : FOG complex

GATA-1 and FOG (Friend of GATA-1) are each essential for erythroid and mega karyocyte development. FOG, a zinc finger protein, interacts with the amino (N) finger of GATA-1 and cooperates with GATA-1 to promote differentiation . To determine whether this interaction is critical for GATA-1 action, we s elected GATA-1 mutants in yeast that fail to interact with FOG but retain n ormal DNA binding, as well a compensatory FOG mutant that restores interact ion. These novel GATA-1 mutants do not promote erythroid differentiation of GATA-1(-) erythroid cells. Differentiation is rescued by the second-site F OG mutant. Thus, interaction of FOG with GATA-1 is essential for the functi on of GATA-1 in erythroid differentiation. These findings provide a paradig m for dissecting protein-protein associations involved in mammalian develop ment.