Evolutionary conservation of gene structures of the Pax1/9 gene family

Based on amino acid sequence comparisons, Pax1 and Pax9 genes are considere d to form a subgroup of vertebrate Pax genes. We show here that the gene st ructures of mouse Pax1, human PAX9 genes are similar to that of a single Pa x1/9 related gene in Branchiostoma lanceolatum, AmphiPax1. This supports th e hypothesis that Pax1 and Pax9 genes were derived from a single ancestral gene. A refined protein alignment of AmphiPax1, mouse Pax1 and human PAX9 p roteins based on the determined exon boundaries indicates that sequence div ergence at the C-termini may be related to the unique functions of the Pax1 and Pax9 genes in vertebrates. AmphiPax1 is expressed in adult amphioxus i n the pharyngeal endoderm. (C) 2000 Elsevier science B.V. All rights reserv ed.