Cloning and developmental expression of Xenopus cDNAs encoding the Enhancer of split groucho and related proteins

The two full-length cDNAs encoding ESG1 (Enhancer of split groucho) and related AES (Amino Enhancer of split) proteins of 767 and 197 amino acids, respectively, were cloned and sequenced from the African frog Xenopus laevis. The amino acid sequence of Xenopus ESG1 protein had 61% identity to the full-length Drosophila groucho. Xenopus AES protein exhibited 91%, 58% and 48% identity to the mouse AES, amino-terminal regions of Xenopus ESG1 and Drosophila groucho, respectively. Northern blot analysis showed that widespread RNA expression of ESG1 of 2.8 kb, ESG2 of 3.6 kb and AES of 2.2 kb transcripts were seen in adult tissues, whereas ESG1 and AES transcripts of 2.8 kb and 2.2 kb, respectively, were ubiquitously expressed in the developing embryos. The overall structural relationships of ESG and AES proteins among human, mouse, rat, Xenopus and Drosophila were analysed.