Abstract
The subcellular location of hexokinase was investigated in rat kidney. Both soluble and particulate locations are indicated by differential centrifugation. The particulate form is predominant, representing about 80% of the total activity. None of the activity is latent. Density gradient centrifugation followed by marker enzyme analysis reveals the presence of two populations of mitochondria with distinct densities. Hexokinase is associated primarily with the mitochondrial population having the lower density. Association of hexokinase with brush border, plasma membrane, lysosomes, and endoplasmic reticulum is considered unlikely on the basis of density gradient centrifugation and enzyme analysis. About 95% of the hexokinase activity associated with the mitochondrial fraction can be released in soluble form by repeated incubations with glucose 6-phosphate. An incubation time of about 4 min at 30°C is required to achieve a maximal solubilizing effect. Release is accomplished without disrupting the mitochondrial compartments. Hexokinase is released also by treatment of the mitochondrial fraction with increasing concentrations of digitonin. This technique disrupts and differentially releases the mitochondrial compartments. As observed with liver, but in contrast to that observed with tumor, the release of hexokinase from the mitochondrial fraction of kidney does not correlate with the release of enzymes known to mark the mitochondrial membranes or compartments. These studies provide the first critical evidence about the subcellular location of hexokinase in kidney. They show that in this tissue hexokinase is associated primarily with low density mitochondria, a finding that adds credibility to the existence of this discrete population of mitochondria in vivo. Significantly, this association of hexokinase with kidney mitochondria appears unique in that its release on submitochondrial fractionation does not correlate with the release of known mitochondrial marker enzymes. These results are directly relevant to those cells in the kidney which utilize glucose as an energy source. It is suggested that the enhanced glycolytic capacity of these cells may be due, at least in part, to an association of hexokinase with low density mitochondria.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 8917-8923 |
| Number of pages | 7 |
| Journal | Journal of Biological Chemistry |
| Volume | 259 |
| Issue number | 14 |
| State | Published - 1984 |
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ASJC Scopus subject areas
- Biochemistry
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Intracellular localization of rat kidney hexokinase. Evidence for an association with low density mitochondria. / Parry, D. M.; Pedersen, Peter L.
In: Journal of Biological Chemistry, Vol. 259, No. 14, 1984, p. 8917-8923.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Intracellular localization of rat kidney hexokinase. Evidence for an association with low density mitochondria
AU - Parry, D. M.
AU - Pedersen, Peter L
PY - 1984
Y1 - 1984
N2 - The subcellular location of hexokinase was investigated in rat kidney. Both soluble and particulate locations are indicated by differential centrifugation. The particulate form is predominant, representing about 80% of the total activity. None of the activity is latent. Density gradient centrifugation followed by marker enzyme analysis reveals the presence of two populations of mitochondria with distinct densities. Hexokinase is associated primarily with the mitochondrial population having the lower density. Association of hexokinase with brush border, plasma membrane, lysosomes, and endoplasmic reticulum is considered unlikely on the basis of density gradient centrifugation and enzyme analysis. About 95% of the hexokinase activity associated with the mitochondrial fraction can be released in soluble form by repeated incubations with glucose 6-phosphate. An incubation time of about 4 min at 30°C is required to achieve a maximal solubilizing effect. Release is accomplished without disrupting the mitochondrial compartments. Hexokinase is released also by treatment of the mitochondrial fraction with increasing concentrations of digitonin. This technique disrupts and differentially releases the mitochondrial compartments. As observed with liver, but in contrast to that observed with tumor, the release of hexokinase from the mitochondrial fraction of kidney does not correlate with the release of enzymes known to mark the mitochondrial membranes or compartments. These studies provide the first critical evidence about the subcellular location of hexokinase in kidney. They show that in this tissue hexokinase is associated primarily with low density mitochondria, a finding that adds credibility to the existence of this discrete population of mitochondria in vivo. Significantly, this association of hexokinase with kidney mitochondria appears unique in that its release on submitochondrial fractionation does not correlate with the release of known mitochondrial marker enzymes. These results are directly relevant to those cells in the kidney which utilize glucose as an energy source. It is suggested that the enhanced glycolytic capacity of these cells may be due, at least in part, to an association of hexokinase with low density mitochondria.
AB - The subcellular location of hexokinase was investigated in rat kidney. Both soluble and particulate locations are indicated by differential centrifugation. The particulate form is predominant, representing about 80% of the total activity. None of the activity is latent. Density gradient centrifugation followed by marker enzyme analysis reveals the presence of two populations of mitochondria with distinct densities. Hexokinase is associated primarily with the mitochondrial population having the lower density. Association of hexokinase with brush border, plasma membrane, lysosomes, and endoplasmic reticulum is considered unlikely on the basis of density gradient centrifugation and enzyme analysis. About 95% of the hexokinase activity associated with the mitochondrial fraction can be released in soluble form by repeated incubations with glucose 6-phosphate. An incubation time of about 4 min at 30°C is required to achieve a maximal solubilizing effect. Release is accomplished without disrupting the mitochondrial compartments. Hexokinase is released also by treatment of the mitochondrial fraction with increasing concentrations of digitonin. This technique disrupts and differentially releases the mitochondrial compartments. As observed with liver, but in contrast to that observed with tumor, the release of hexokinase from the mitochondrial fraction of kidney does not correlate with the release of enzymes known to mark the mitochondrial membranes or compartments. These studies provide the first critical evidence about the subcellular location of hexokinase in kidney. They show that in this tissue hexokinase is associated primarily with low density mitochondria, a finding that adds credibility to the existence of this discrete population of mitochondria in vivo. Significantly, this association of hexokinase with kidney mitochondria appears unique in that its release on submitochondrial fractionation does not correlate with the release of known mitochondrial marker enzymes. These results are directly relevant to those cells in the kidney which utilize glucose as an energy source. It is suggested that the enhanced glycolytic capacity of these cells may be due, at least in part, to an association of hexokinase with low density mitochondria.
UR - http://www.scopus.com/inward/record.url?scp=0021200293&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0021200293&partnerID=8YFLogxK
M3 - Article
C2 - 6746630
AN - SCOPUS:0021200293
VL - 259
SP - 8917
EP - 8923
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 14
ER -