GENOMIC ORGANIZATION AND CHROMOSOME LOCALIZATION OF THE MURINE HOMEOBOX GENE PMX

Homeobox genes are expressed in very specific temporal and spatial pat terns and function as transcriptional regulators of developmental proc esses. The murine homeobox gene, Pmx (paired mesoderm homeobox), is ex pressed in a mesodermally restricted pattern in embryos and most abund antly in cardiac, skeletal, and smooth muscle tissues in adults. Previ ously, this murine gene was named K-2 and mHox, while the human homolo g was named Phox1. In this report, the localization of Pmx has been de termined by interspecific backcross analysis. The Pmx gene is located on Chromosome 1, approximately 3.3 cM distal to the Gsh-4 homeobox loc us. The sequence of the Pmx transcript has been extended toward the 5' end and corresponds in size to one of the transcripts previously dete cted by Northern blot analysis. Sequence analysis indicates that Pmx i s the first characterized mammalian gene to encode a paired type homeo domain, but not a paired domain. The Pmx gene includes at least five e xons spanning a minimum of 60 kb of genomic DNA, making this the large st known murine homeobox gene. (C) 1994 Academic Press,Inc.