Section 7
Chapter 6,593

Tetrahymena pyriformis cells are deficient in all mannose p dolichol dependent mannosyltransferases but not in mannose p dolichol synthesis

Parodi A.J.

Biochemistry 26(18): 5937-5943


ISSN/ISBN: 0006-2960
DOI: 10.1021/bi00392a054
Accession: 006592129

Download citation:  

Cells of the ciliated protozoan Tetrahymena pyriformis incubated with [14C]glucose were found to synthesize Man-P-dolichol and Glc-P-dolichol, as well as Glc3Man5GlcNAc2-P-P-dolichol, the latter being the main and largest lipid derivative formed. The missing mannose residues were those known to be transferred from Man-P-dolichol in other systems. Formation of Man-P-dolichol and of dolichol-P-P-oligosaccharides containing up to five mannose units was detected in cell-free assays containing protozoan membranes, rat liver dolichol-P, unlabeled Man4-9GlcNAc2-P-P-dolichol from pig liver, and GDP-[14C]Man. Under exactly the same conditions but with UDP-[14C]Glc instead of GDP-[14C]Man, Glc-P-dolichol and dolichol-P-P-oligosaccharides containing five mannose and one to three glucose residues were formed in the absence of the pig liver compounds. In the presence of the latter, dolichol-P-P derivatives containing nine mannose and one to three glucose units were also synthesized. It is concluded that T. pyriformis cells are deficient in all Man-P-dolichol-dependent mannosyltransferases but not in Man-P-dolichol synthesis. The role of the later compound in this microorganism is unknown.

PDF emailed within 0-6 h: $19.90