Deglycosylated membranous and soluble dopamine beta-hydroxylase have identical apparent molecular weights.
Dopamine beta-hydroxylase exists as soluble and membrane-bound forms in secretory vesicles. The soluble form of the enzyme contains identical subunits of 72 kDa and the membrane-bound form contains two non-identical subunits of 72 kDa and 75 kDa. The difference in the banding pattern on sodium dodecyl sulfate-polyacrylamide gel electrophoresis suggests the presence of either an extra peptide, or membrane-binding segment, or differential glycosylation of 75-kDa subunits of the membranous form. Soluble and membranous forms of the enzyme were deglycosylated with endoglycosidases to elucidate the contribution of the carbohydrate moieties to the banding pattern on a sodium dodecyl sulfate-polyacrylamide gel. The deglycosylated species of both forms appeared to be identical and showed a decrease in apparent molecular weights to 66 kDa. These results indicate that the banding pattern of soluble and membranous dopamine beta-hydroxylase on sodium dodecyl sulfate-polyacrylamide gel electrophoresis may not be due to a membrane-binding anchor but rather to carbohydrate moieties.
Oyarce
A M
AM
Department of Biochemistry, Georgetown University Medical Center, Washington, DC 20007.
Fleming
P J
PJ
D000313:Adrenal Medulla / Q000201:enzymology*; D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D004299:Dopamine beta-Hydroxylase / Q000302:isolation & purification*; D004591:Electrophoresis, Polyacrylamide Gel; D006026:Glycoside Hydrolases; D006031:Glycosylation; D007527:Isoenzymes / Q000302:isolation & purification*; D037102:Lectins; D046911:Macromolecular Substances; D008970:Molecular Weight
D007527:Isoenzymes; D037102:Lectins; D046911:Macromolecular Substances; D004299:Dopamine beta-Hydroxylase; D006026:Glycoside Hydrolases