Why humans and Catarrhini lack the Galα1-3Gal epitope, related to xenograft rejection?

• Main Authors: Anna Suchanowska, Marcin Czerwiński
• Format: Article
• Language: English
• Published: Index Copernicus International S.A. 2009-06-01
• Series: Postępy Higieny i Medycyny Doświadczalnej
• Subjects: Galα1-3Gal epitope; α1; 3-galactosyltransferase; pseudogene; GGTA1; xenotransplant
• Online Access: http://journals.indexcopernicus.com/fulltxt.php?ICID=887414

The Galα1-3Gal epitope (Galβ1-3Galα1-4GlcNAc-R) is an oligosaccharide determinant present on the cell surface of most mammalian species with the exception of the higher primates, including Old World monkeys, apes, and humans. The synthesis of Galα1-3Gal epitope is catalyzed by α1,3-galactosyltransferase (α1,3GT). Inactivation of the α1,3GT gene in humans and the production of natural anti-Gal1-3Gal antibodies against the Galα1-3Gal epitope has resulted in the formation of a unique immunological barrier that prevents the transplantation of tissues and organs from Galα1-3Gal-positive animals to humans. The gene encoding α1,3-galactosyltransferase in higher primates is inactive due to point mutations and deletions leading to a change of reading frame. The human transcript of this gene consists of several splicing variants, most of which does not contain an exon encoding the catalytic domain. Thus no active protein is produced.