Identification of an endogenous inhibitor of the UDP-N-acetylgalactosamine : GM3, N-acetylgalactosaminyl transferase as apolipoprotein A1

• Published in: Neurochemical research Vol. 22; no. 4; pp. 483 - 490
• Main Authors: CONDE, C. B, GRABOIS, V. R, DEZA, S. N, CAPUTTO, B. L
• Format: Journal Article
• Language: English
• Published: New York, NY Springer 01-04-1997; Springer Nature B.V
• Subjects: Amino Acid Sequence; Animals; Antibodies, Monoclonal - pharmacology; Apolipoprotein A-I - chemistry; Apolipoprotein A-I - isolation & purification; Apolipoprotein A-I - pharmacology; Apolipoproteins; Biological and medical sciences; Brain - drug effects; Cells, Cultured; Chick Embryo; Electrophoresis, Polyacrylamide Gel; Fundamental and applied biological sciences. Psychology; Galactose - metabolism; Gangliosides - biosynthesis; Isolated neuron and nerve. Neuroglia; Molecular Sequence Data; N-Acetylgalactosaminyltransferases - antagonists & inhibitors; Neurons - drug effects; Peptide Fragments - chemistry; Peptide Fragments - isolation & purification; Peptide Fragments - pharmacology; Polypeptide N-acetylgalactosaminyltransferase; Polypeptides; Proteins; Tritium; Vertebrates: nervous system and sense organs; Enzyme; Transferases; Glycosyltransferases; Central nervous system; Apolipoprotein AI; Enzyme inhibitor; In vitro; Blood; Vertebrata; Neuron; Serum; Hexosyltransferases; Chicken; Aves; (N-Acetylneuraminyl)-galactosylglucosylceramide N-acetylgalactosaminyltransferase; Brain (vertebrata)
• ISSN: 0364-3190; 1573-6903
• DOI: 10.1023/A:1027320113151

A previously described inhibitor of the UDP-N-acetylgalactosamine: GM3, N-acetylgalactosaminyltransferase (GalNAc-T) (Quiroga et al., 1, 2), was purified from chicken blood serum by a new procedure. When subjected to SDS-PAGE, two major polypeptides of 27 and 70 kDa were observed. When tested in vitro, only the 27 kDa polypeptide inhibited the GalNAc-T. When added to chick cerebral embryonic neurons in culture, both polypeptides inhibited neuritogenesis. Both the 27 kDa and the 70 kDa fractions were present in the cells at 3 h following their addition to the cultures; both polypeptides had aneuritogenic activity and both inhibited the incorporation of [3H]-galactose into the cell gangliosides modifying their labeling pattern to a similar extent. Sequencing of the amino terminal end of the polypeptides showed that 18 and 9 amino acids from, respectively, the 27 and the 70 kDa polypeptides, were 100% homologues with the corresponding region of chick apolipoprotein Al (apo Al). After addition to cells in culture, no interconversion between the two polypeptides was detected after up to 20 h in culture. A monoclonal antibody that recognizes only the 70 kDa polypeptide, blocks its aneuritogenic effect without modifying that of the 27 kDa fraction. It is concluded that the endogenous inhibitor of GalNAc-T is apo Al.