Localization of trehalase in flight muscle of the blowfly Phormia regina

• Published in: Archives of biochemistry and biophysics Vol. 145; no. 1; pp. 392 - 401
• Main Authors: Reed, W.Douglas, Sacktor, Bertram
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.1971
• Subjects: Adenosine Diphosphate; Adenosine Monophosphate; Adenosine Triphosphate; Animals; arthropods; Centrifugation, Density Gradient; Digitalis Glycosides; Diptera; entomology; Freezing; Glycerolphosphate Dehydrogenase; Glycoside Hydrolases; Hexokinase; insects; Malate Dehydrogenase; Membranes - enzymology; Microscopy, Electron; Mitochondria, Muscle - enzymology; Muscles - cytology; Muscles - enzymology; Phosphotransferases; Saponins; Spirostans; Subcellular Fractions - enzymology; Trehalase; Ultracentrifugation
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1016/0003-9861(71)90052-X

The ultrastructural localization of trehalase in the flight muscle of the blowfly, Phormia regina, has been investigated. Approximately 65% of the total activity sediments with a low-speed pellet; 25% of the activity in the homogenate is soluble. The activity in the particulate fraction resides in the mitochondria. Isolated mitochondria have been fractionated by different procedures and the distribution of trehalase has been compared to the distributions of α-glycerophosphate dehydrogenase, hexokinase binding, malic dehydrogenase, and adenylate kinase, representing the inner and outer membranes, the matrix, and the space between the outer and inner membranes of the mitochondria, respectively. Trehalase is clearly separated from the enzyme markers of the matrix and the space between the two membranes. Its distribution closely resembles that of α-glycerophosphate dehydrogenase rather than that of hexokinase binding. Thus, these findings support the tentative conclusion that in blowfly flight muscle the mitochondrial trehalase is localized on the inner membrane. If the permeability of trehalose in mitochondria is the same as that of sucrose, then it is suggested that trehalase is situated on the outside of the mitochondrial inner membrane. The evidence to-date favors the view that the soluble trehalase activity in muscle homogenates represents a muscle enzyme distinct from the mitochondrial trehalase.