The NF-E2-binding sites or Maf recognition elements (MARE) are essential cis-acting elements in the regulatory regions of erythroid-specific genes recognized by the erythroid transcription factor NF-E2, composed of p45 and MafK. Recently, two p45-related factors Nrf1 and Nrf2 were isolated, and they are now collectively grouped as the Cap'n' collar (CNC) family. CNC factors bind to MARE through heterodimer formation with small Maf proteins. We report here the identification and characterization of a novel CNC factor, Nrf3, encoding a predicted 73-kDa protein with a basic regionleucine zipper domain highly homologous to those of other CNC proteins. In vitro and in vivo analyses showed that Nrf3 can heterodimerize with MafK and that this complex binds to the MARE in the chicken ␤-globin enhancer and can activate transcription. Nrf3 mRNA is highly expressed in human placenta and B cell and monocyte lineage. Chromosomal localization of human Nrf3 is 7p14 -15, which lies near the hoxA gene locus. As the genetic loci of p45, nrf1, and nrf2 have been mapped close to those of hoxC, hoxB, and hoxD, respectively, the present study strongly argues for the idea that a single ancestral gene for the CNC family members may have been localized near the ancestral Hox cluster and have diverged to give rise to four closely related CNC factors through chromosome duplication.

SummaryWe have. id.entified a partial deletiotl of the 8hart arm of chromosome 20 in a .5-ye.0r~-o!d boy from pareu.t~ having norm~! phenotype and ka~otype, Hi~ major anomalies were mild .mer~tal retardation, eongenita! be.art di~sease., chest deformity, s~pina bifido, kyphosco!io~is, inguinal hernia, and preaurjcula.r fistula, Th# c.lin, ic0! findings were tompared with those of two patLe0t~ r~eport~d pre~viou_s!y o~ a partial deletion 20p.T~ activity of adeno.sine deamin.ase in the patJent'~ red blood r162 was within normal range, sugge~sting that the gene. locus for the enzyme, which has been pr~evioosly as_signr to ~hromosom~ 20, may not pre.sent on pl !--*pter of chromosome 20,

SummaryA girl with growth and mental retardation, ventricular dilatation, hypoplastic brain, and other minor anomalies was found to have a 46,XX,t(3p-;18qq-) karyotype. G-, Q-, and R-band analyses and measurements of chromosome length revealed a partial deletion del(3) (p13p21), in addition to the translocation. Her karyotype was 46,XX,del(3), t(3; 18) (3qter--* 3p 13: :18q23--~ 18qter; 18pter---~ 18q23 : :3p21 ~ 3pter) according to the Paris and Stockholm Conference nomenclature.

The newly emerged Maf family proteins possess a highly conserved basic leucine zipper (bZip) domain in common and are subdivided into large and small Maf proteins. The Maf family proteins appear to regulate cell differentiation processes and also cellular functions as partner molecules of CNC family proteins. To facilitate understanding of the function of small Maf proteins, we isolated the genes (MAFG and MAFK) encoding human small Maf proteins MafG and MafK and characterized their structures and organization by means of restriction enzyme mapping, Southern blot hybridization and nucleotide sequence analysis. Organization of the small maf genes are highly conserved in vertebrates, suggesting an important functional contribution of the gene products. We also examined the location of these genes within the human genome by fluorescence in situ hybridization (FISH) analysis. Human MAFG and MAFK are located at 17q25 and 7p22, respectively. Thus, small maf genes are not clustered in a single locus.

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