Sialidase occurs in both membranes of the nuclear envelope and hydrolyzes endogenous GD1a.
Previous reports indicated the presence of both gangliosides and sialidase in the nuclear envelope (NE) of primary neurons and the NG108-15 neural cell line. GM1, one of the major gangliosides of this membrane, was shown to be tightly associated with a sodium-calcium exchanger in the inner membrane of the NE and to potentiate exchanger activity. GD1a was the other major ganglioside detected in the NE and, like GM1, occurs in both inner and outer membranes. A subsequent report indicated the presence of sialidase activity in the NE without specification as to which of the two membranes express it. The present study was undertaken to determine the nature and locus of this activity within the NE of two cell lines: NG108-15 and SH-SY5Y. Western blot analysis of the separated membranes revealed occurrence of Neu3 in the inner membrane and Neu1 in the outer membrane of the NE. Moreover, sialidase activity at both sites was shown capable of catalyzing conversion of endogenous GD1a to GM1.
Wang
Jianfeng
J
Department of Neurology & Neurosciences, New Jersey Medical School, UMDNJ, Newark, New Jersey 07103, USA.
Wu
Gusheng
G
Miyagi
Taeko
T
Lu
Zi-Hua
ZH
Ledeen
Robert W
RW
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D000918:Antibody Specificity; D015153:Blotting, Western; D045744:Cell Line, Tumor; D005732:Gangliosides / Q000378:metabolism*; D005910:Glioma; D006801:Humans; D006822:Hybrid Cells; D006868:Hydrolysis; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000276:immunology / Q000378:metabolism*; D009439:Neuraminidase / Q000276:immunology / Q000378:metabolism*; D009447:Neuroblastoma; D009685:Nuclear Envelope / Q000201:enzymology*; D012377:Rodentia; D013379:Substrate Specificity
D000906:Antibodies; D005732:Gangliosides; D007527:Isoenzymes; C021298:ganglioside, GD1a; C486385:NEU1 protein, human; C110128:Neu1 protein, mouse; C465436:Neu3 protein, human; C511796:Neu3 protein, mouse; D009439:Neuraminidase