The N-glycosylation mutants (mnnl and mnn1 ochl) show different morphological characteristics at the restrictive and nonpermissive temperature. We deleted the MNN1 to eliminate the terminal alpha 1, 3-linked mannose of hypermannosylation and deleted the OCH1 to block the elongation of the main backbone chain. The mnn1 cells exhibited no observable change with respect to the wildtype strain at 28 degrees C and 37 degrees C, but the mnn1 och1 double mutant exhibited defects in cell cytokinesis, showed a slower growth rate, and became temperature-sensitive. Meanwhile, the mnn1 ochl mutant tended to aggregate, which was probably due to the glycolsylation defect. Loss of mannosyl-phosphate-accepting sites in this mutant migth result in reduced charge repulsion between cell surfaces. Pyridylaminated glycans were profiled and purified through an NH2 column by size-fractionation high-performance liquid chromatography. Matrix assisted laser desoption/ionization time of flight mass spectrometry (MALDI TOF/ MS) analysis of the N-glycan structure of the mnnl ochl mutant revealed that the main component is Man(8)GIcNAc(2).