A comparison of the subcellular distribution of 5′-nucleotidase, (Na+K+)-ATPase and adenyl cyclase in beef thyroid gland |
| |
Authors: | S. Matsuzaki R. Pochet E. Schell-Frederick |
| |
Affiliation: | Institut de Recherche Interdisciplinaire (LMN), School of Medicine, University of Brussels, 1000 Brussels, Belgium |
| |
Abstract: | The validity of 5′-nucleotidase as a plasma membrane marker enzyme in beef thyroid has been tested by comparing the subcellular distribution of its activity to that of (Na+K+)-activated ATPase and adenyl cyclase. The specific activity and total activity of (Na+K+)-ATPase and adenyl cyclase were greatest in the 1000 × g (“nuclear”) and 33 000 × g (“mitochondrial and lysosomal”) fractions. In contrast, 5′-nucleotidase activity was concentrated in the 165 000 × g (“microsomal”) pellet and supernatant. Partially purified plasma membranes were separated from the 1000 (N2), 30 000 (M2) and 165 000 × g (P2) pellets by discontinuous sucrose gradient centrifugation. Again a discordant distribution of these enzyme activities was observed. (Na+K+)-ATPase specific activity was increased approximately 30-fold over the homogenate in Fractions N2 and M2. Basal, thyroid-stimulating hormone-and fluoride-stimulated adenyl cyclase activities were concentrated in the same fractions. 5′-Nucleotidase activity was preferentially located in M2 and P2. These differences in distribution pattern suggest that 5′-nucleotidase activity is not uniquely located in the plasma membrane in the thyroid. |
| |
Keywords: | |
本文献已被 ScienceDirect 等数据库收录! |
|