IIBBA   05544
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE BUENOS AIRES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Preferential transfer of the complete glycan is determined bythe oligosaccharyltransferase complex
Autor/es:
CASTRO OLGA, MOVSICHOFF FEDERICO AND PARODI ARMANDO J.
Lugar:
Rosario
Reunión:
Congreso; LII Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology; 2006
Institución organizadora:
Sociedad Argentina de Bioquímica y Biología Celular
Resumen:
Most eukaryotic cells show a strong preference for the transfer in vivo and in vitro of the largest dolichol-P-P-linked glycan (Glc3Man9GlcNAc2) to protein chains over that of biosynthetic intermediates that lack the full complement of glucose units. The oligosaccharyltransferase (OST) is a multimeric complex containing eight different proteins, one of which (Stt3p) is the catalytic subunit. Trypanosomatid protozoa lack an OST complex and express only this last protein. Contrary to the OST complex from most eukaryotic cells, the Stt3p subunit of these parasites transfers in cell-free assays glycans with Man7–9GlcNAc2 and Glc1–3Man9GlcNAc2 compositions at the same rate. We have replaced Saccharomyces cerevisiae Stt3p by the Trypanosoma cruzi homologue and found that the complex that is formed preferentially transfers the complete glycan both in vivo and in vitro. Thus, preference for Glc3Man9GlcNAc2 is a feature that is determined by the complex and not by the catalytic subunit.