ALX-4 - CDNA CLONING AND CHARACTERIZATION OF A NOVEL PAIRED-TYPE HOMEODOMAIN PROTEIN

Homeodomain containing transcription factors serve important functions in patterning the embryo during vertebrate development. We have isola ted cDNA clones encoding a novel protein, named A1x-4, that contains a paired-type homeodomain. Analysis of the homeodomain sequence shows t hat A1x-4 belongs to a family of genes that are related to the Drosoph ila gene aristaless, and includes the mammalian genes A1x3, Cart-1, MH ox, and S8. We have analyzed the expression of A1x-4 during developmen t by Northern blot and whole mount in situ hybridization. In addition, we have generated antibodies to recombinant A1x-4 protein and identif ied A1x-4 protein in nuclear extracts prepared from mouse embryos. The expression pattern of A1x-4 suggests that it may play a role in the p atterning of structures derived from craniofacial mesenchyme, the firs t branchial arch, and the limb bud. Our results provide a starting poi nt for the analysis of a new member of the family of paired type homeo domain proteins. (C) 1997 Elsevier Science B.V.