6 MEMBERS OF THE MOUSE FORKHEAD GENE FAMILY ARE DEVELOPMENTALLY-REGULATED

The 110-aa forkhead domain defines a class of transcription factors th at have been shown to be developmentally regulated in Drosophila melan ogaster and Xenopus laevis. The forkhead domain is necessary and suffi cient for target DNA binding as shown for the rat hepatic nuclear fact or 3 (HNF3) gene family. We have cloned six forkhead gene family membe rs from a mouse genomic library in addition to the mouse equivalents o f the genes for RNF3alpha, -beta, and -gamma. The six genes, termed fk h-1 to fkh-6, share a high degree of similarity with the Drosophila fo rkhead gene, having 57-67% amino acid identity within the forkhead dom ain. fkh-1 seems to be the mammalian homologue of the Drosophila FD1 g ene, as the sequences are 86% identical. fkh-1 to fkh-6 show distinct spatial patterns of expression in adult tissues and are expressed duri ng embryogenesis.