Protein characterization and targeted disruption of Grg, a mouse gene related to the groucho transcript of the Drosophila enhancer of split complex

The Grg gene encodes a 197 amino acid protein homologous to the amino-terminal domain of the product of the groucho gene of the Drosophila Enhancer of split complex. Analysis with a polyclonal antisera specific for the Grg protein revealed that Grg is a 25 kd nuclear protein that can participate in specific protein-protein interactions. A null mutation of the Grg gene was constructed by gene targeting. Mice homozygous for this mutation completed embryogenesis and were born, but exhibited varying degrees of post-natal growth deficiency. No dosage-sensitive genetic interaction was detected between the Notch1 and Grg genes in mice heterozygous for a Notch1 mutant allele and homozygous for the Grg null mutation.