FINE-STRUCTURE OF THE HUMAN GALACTOKINASE GALK1 GENE

Defects in the human GALK1 gene result in galactokinase deficiency and cataract formation. We have isolated this gene and established its st ructural organization. The gene contains 8 exons and spans similar to 7.3 kb of genomic DNA. The GALK1 promoter was localized and found to h ave many features in common with other housekeeping genes, including h igh GC content, several copies of the binding site for the Spl transcr iption factor, and the absence of TATA-box and CCAAT-box motifs typica lly present in eukaryotic Pol II promoters. Analysis by 5'-RACE PCR in dicates that the GALK1 mRNA is heterogeneous at the 5' terminus, with transcription sites occurring at many locations between 21 and 61 bp u pstream of the ATG start site of the coding region. In vitro translati on experiments of the GALK1 cDNA indicate that the protein is cytosoli c and not associated with the endoplasmic reticulum membrane.