Figure 2

Human paralogons of the LBX/TLX cluster loci. Schematic representation of the four human LBX/TLX paralogons plus paralogous genes occurring at the NKX3.2 locus, deduced from analysis of the human genome using NCBI map viewer Homo sapiens Build 36.2 (September 2006). Genes are represented by boxes with gene names appearing above and gene subfamilies indicated by numbers inside. Letters on the far left indicate paralogon designation, while chromosomal locations are indicated on the far right. Numbers between genes are approximate intergenic distances in Kb. Background shading indicates paralogous genes. Blue and red dots indicate sites of inversions. Note that LOXL1, AUP1 and PCGF1 genes appear only at the LBX2 locus and KAZALD1, POLL, DPCD, FBXW4 and MGEA5 appear only at the LBX1 locus. BTRC, FGF, NPM and KCNIP genes are linked with LBX and TLX genes at more than one locus, suggesting that these genes were acquired by the LBX/TLX cluster during or before the two rounds of vertebrate genome duplication. Also note that a KCNIP4 and a SLIT2 gene are associated with NKX3.2 on chromosome 4. A KCNIP3 gene is located on the long arm of chromosome2, however at a distance to LBX2, suggesting that it is not an original component of the LBX2 paralogon.