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Characterization of Soluble Neural Cell Adhesion Molecule in Rat Brain, CSF, and Plasma
Author(s) -
Krog Lisbeth,
Olsen Marianne,
Dalseg AnneMarie,
Roth Jürgen,
Bock Elisabeth
Publication year - 1992
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1992.tb08321.x
Subject(s) - neural cell adhesion molecule , glycosylation , epitope , gene isoform , biochemistry , transmembrane protein , chemistry , extracellular , cell adhesion molecule , monoclonal antibody , peptide , cell adhesion , microbiology and biotechnology , antibody , biology , cell , immunology , gene , receptor
The polypeptide composition and glycosylation of soluble isoforms of neural cell adhesion molecule (NCAM) in developing rat brain, CSF, and plasma were characterized. Soluble NCAM in rat brain consisted of several glycosylated isoforms. The degree of glycosylation was developmentally regulated. After desialylation, four polypeptides of M r values of ∼ 190,000 (sl), 135,000 (s2), 115,000 (s3), and 110,000 (s4) were observed. Polypeptides si, s2, and s3 were also present in CSF, whereas only s3 and s4 were observed in plasma. Treatment of soluble brain NCAM with N ‐glycosidase F, which removes N ‐linked carbohydrates, produced polypeptides of M r values of ∼ 190,000, 125,000, and 108,000–97,000. The monoclonal antibody OB11, which recognizes an epitope on the cytoplasmic part of transmembrane forms of NCAM, did not react with any of the soluble isoforms. Purified soluble NCAM, consisting mainly of s3, contained an N ‐terminal sequence identical to that of membrane‐associated NCAM. Gel nitration of s3 indicated that it was present as a dimer under the chosen conditions. NCAM‐expressing glioma cells adhered specifically to immobilized soluble NCAM. This implies that functionally significant soluble forms of NCAM are present in the extracellular fluid.