The glycerol kinase gene family: structure of the Xp gene, and related intronless retroposons

Abstract

The human glycerol kinase gene family consists of at least six genomic loci, four of which encode expressed sequences. The X-linked gene responsible for GKD maps to Xp21.3. Analysis of cosmid and YAC clones shows that this locus is in excess of 50 kbp, and is comprised of 19 exons. In contrast, the remaining members of the gene family, on chromosomes 1, 4 and Xq, appear to be organized as intronless genes. Northern analysis shows expression of GK transcripts of three sizes in a wide range 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 chromosome 4.

Structural and functional analysis of the promoters of the human glycerol kinase gene family

“…It is interesting to note that GK-Xp is most highly expressed in the liver, kidney and muscle, whereas the GK-1 and GK-2 are only transcribed in the germ cells. These results, therefore, are entirely consistent with the results observed by Northern blot analysis (Sargent et al, 1994). The result also suggests that the basis of the differential activity probably reside in the 5' flanking sequences and, that the element(s) is contained within the 1 kb fragments of the GK-1 and GK-2 genes and the 350 bp of the GK-Xp gene.…”

“…Thus, Northern hybridisation analyses of human male adult tissues and clones isolated from a human testis cDNA library have revealed at least two testis-specific glycerol kinase genes. Both of these testis-specific transcripts mapped to chromosome 4 (Sargent et al, 1994). The mouse homologue of these genes has recently, also, been identified (Pan et al, 1999).…”

“…In mammals, GK activity has mainly been identified in liver and kidney and, at low levels, in intestinal mucosa, adipose tissue, cardiac and skeletal tissues (McCabe, 1989). The gene encoding human glycerol kinase expressed in somatic tissues was isolated by several groups, and has been mapped to the short arm of the X-chromosome (Guo, 1993;Walker et al, 1993;Sargent et al, 1994). However, the X-chromosome is inactivated at specific stages during spermatogenesis.…”

“…Repeated cDNA analyses of both somatic and testis tissues have shown that the GK genes are differentially expressed. GK-Xp is predominantly expressed in somatic tissues, such as kidney and liver, whereas GK-1 and GK-2 on chromosome 4, are specifically expressed in the testis (Sargent et al, 1994), a result expected because of X-inactivation (McCarrey et al, 1996;Erickson, 1993).…”

hyperglycérolémie familiale au Saguenay-Lac-Saint-Jean :

“…Ainsi, l'ingestion de glycéro! durant la pratique de sports d'endurance permettrait d'améliorer significativement l'endurance, augmenterait la résistance de l'organisme face à une hausse de température corporelle et favoriserait une thermorégulation plus efficace (Robergs étal., 1998;Wagner, 1999 Le gène codant pour la GK se situe sur le chromosome Xp21.3 (Walker et al, 1993;Sargent et al, 1994;Gaudet et al, 2000;McCabe, 2000;Sjarif et al, 2000). !I existe trois formes cliniques différentes de déficience en GK, soit la forme infantile, aussi connue sous le nom de forme complexe, de même que les formes juvénile et adulte.…”