Ceruloplasmin carries the anionic glycan oligo/poly alpha2,8 deaminoneuraminic acid.
Oligo/poly alpha2,8 deaminoneuraminic acid (KDN), a unique posttranslational protein modification, was found on megalin and a not yet characterized 150 kDa glycoprotein. We purified this glycoprotein from rat testis and identified it as ceruloplasmin. Furthermore, immunoprecipitated ceruloplasmin from rat thymus, ovary, blood serum, and postnatal day 2 but not adult lung and brain was immunoreactive for oligo/poly alpha2,8 KDN. The immunoreactivity for oligo/poly alpha2,8 KDN on purified serum ceruloplasmin was abolished by N-glycosidase F treatment but not by beta-elimination, indicating that it is present on N-glycosidically linked oligosaccharides. However, the copper binding activity of ceruloplasmin was independent of the presence of the anionic glycan. By immunohistochemistry, ceruloplasmin was detectable in histologically defined regions in rat ovary, thymus, and spleen. Likewise, by RT-PCR, ceruloplasmin expression was found in various non-hepatic rat tissues and showed a developmentally regulated pattern. Thus, ceruloplasmin, in addition to megalin, represents a glycoprotein carrying oligo/poly alpha2,8 KDN.
Ziak
Martin
M
Division of Cell and Molecular Pathology, Department of Pathology, University of Zürich, Switzerland. martin.ziak@pty.usz.ch
Meier
Mirjam
M
Novak-Hofer
Ilse
I
Roth
Jürgen
J
D000581:Amidohydrolases / Q000494:pharmacology; D000818:Animals; D000838:Anions; D001059:Apoproteins / Q000378:metabolism; D002570:Ceruloplasmin / Q000737:chemistry* / Q000378:metabolism*; D003300:Copper / Q000378:metabolism; D004587:Electrophoresis, Agar Gel; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D007150:Immunohistochemistry; D008024:Ligands; D008099:Liver / Q000378:metabolism; D010053:Ovary / Q000378:metabolism; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D016133:Polymerase Chain Reaction; D011134:Polysaccharides / Q000737:chemistry*; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013154:Spleen / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D013950:Thymus Gland / Q000378:metabolism; D014018:Tissue Distribution
D000838:Anions; D001059:Apoproteins; D008024:Ligands; D011134:Polysaccharides; D012333:RNA, Messenger; C006612:apoceruloplasmin; C099023:poly(2,8-deaminoneuraminic acid); D003300:Copper; D002570:Ceruloplasmin; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase