THE HUMAN VIGILIN GENE - IDENTIFICATION, CHROMOSOMAL LOCALIZATION ANDEXPRESSION PATTERN

Chick vigilin cRNA clones were used to isolate the cognate human gene, by screening a pWE15 genomic library. Three independent cosmid clones were isolated and characterized by restriction mapping. The gene was identified by sequencing an internal EcoRI fragment containing two exo ns homologous to exon 24 and 25 of the chicken vigilin gene and corres ponding to nucleotides 1973-2104 of the human HBP-cDNA. The homology b etween the chicken and human sequences was 77% and 82% at the cDNA lev el, and 91% and 100% at the amino acid level. In addition, the analyze d intron/exon boundaries were invariantly conserved. The 5' and 3'regi ons of the human gene were mapped by Southern analysis of the respecti ve clones with synthetic oligonucleotides. The entire vigilin gene spa ns a region of about 50 kb and has been assigned to chromosome 2q36-q3 7.2 (FL-pter value of 0.96 +/- 0.03) by fluorescence in situ hybridiza tion to metaphase spreads from normal peripheral blood lymphocytes. Th e vigilin gene is localized in a chromosomal region comprising a clust er of collagen genes (COLIVA3, COLVIA3) and the locus of the Waardenbu rg syndrome I. Only one mRNA species of 4.4 kb is transcribed from the human vigilin gene. In accordance with previous observations on chick en mRNA, the expression of the human vigilin mRNA depends on the stage of cytodifferentiation both in vitro and in situ.