[Soluble and membrane-bound neutral alpha-glucosidase from the human kidney].
In human kidney cortex neutral alpha-glucosidases 1 and 2 are represented by two forms, soluble (cytosolic) and membrane-bound (brush border) ones. It has been shown that the soluble enzyme preexists in human kidney but does not derive from the membrane-bound form. Similar to the membrane-bound enzyme the soluble form is a glycoprotein. Both enzyme forms possess identical electrophoretic mobility, pH-optimum, heat sensibility and Km values for maltose (0.7 mM) and 4-methylumbelliferyl-alpha-D-glucopyranoside (0.57 mM), but differ by molecular weights as determined by gel filtration chromatography. The molecular weights of the soluble neutral alpha-glucosidases 1 and 2 are lower than those of the comparable brush border enzymes (470 000, 360 000, 520 000 and 440 000, correspondingly). Neutral membrane-bound alpha-glucosidase 1 is a sialylated enzyme with a pI of 4.10 +/- 0.02. The soluble enzyme contains no or only traces of neuraminic acid and has a pI 4.40 +/- 0.03. The soluble and membrane-bound neutral alpha-glucosidases are apparently independent forms of the enzyme, differing by the degree of sialylation and by the presence of an "anchor" in the membrane-bound enzyme. The synthesis of both forms is presumably coded by the same structural gene.
D002462:Cell Membrane / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D004355:Drug Stability; D005959:Glucosidases / Q000302:isolation & purification*; D006358:Hot Temperature; D006801:Humans; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism; D007672:Kidney Cortex / Q000201:enzymology*; D007700:Kinetics; D008871:Microvilli / Q000201:enzymology; D008970:Molecular Weight; D013379:Substrate Specificity; D000520:alpha-Glucosidases / Q000302:isolation & purification* / Q000378:metabolism
D007527:Isoenzymes; D005959:Glucosidases; D000520:alpha-Glucosidases
Rastvorimaia i membranosviazannaia neĭtral'naia al'fa-gliukozidaza pochek cheloveka.