THE GLYCEROL KINASE GENE FAMILY - STRUCTURE OF THE XP GENE, AND RELATED INTRONLESS RETROPOSONS

The human glycerol kinase gene family consists of at least six genomic loci, four of which encode expressed sequences. The X-linked gene res ponsible for GKD maps to Xp21.3. Analysis of cosmid and YAC clones sho ws that this locus is in excess of 50 kbp, and is comprised of 19 exon s. In contrast, the remaining members of the gene family, on chromosom es 1, 4 and Xq, appear to be organized as intronless genes. Northern a nalysis shows expression of GK transcripts of three sizes in a wide ra nge of adult tissues. Only the smallest hybridizing species is present in testis where it occurs at an elevated level. Two different testis transcripts have been identified and both of these originate from chro mosome 4.