The Arabidopsis tonoplast is almost devoid of N-glycosylated proteins, unlike the rat lysosomal membrane

About one third of secretory proteins are N-glycosylated and N-glycans can be modified when proteins travel through the Golgi complex. Using in silico and experimental approaches we analyzed the distribution of the N-glycoproteome in the vacuolar (tonoplast) or plasma membrane (PM) of Arabidopsis. We showed that the tonoplast is virtually devoid of proteins with Golgimodified glycans and contains only a small proportion, if any, of the N-glycoproteome, which is instead enriched in the PM. Lysosomes share with vacuoles the hydrolytic functions and the position along the secretory pathway. However, we showed that the percentage of Nglycoproteome of the rat lysosomal and plasma membranes are very similar, and much higher than that of the tonoplast. We propose that protection against the luminal hydrolases, which seems to have been achieved in lysosomal membrane proteins by extensive N-glycosylation, has instead been mainly obtained in tonoplast proteins by limiting the length of luminal domains.