Protein specific N-glycosylation of tyrosinase and tyrosinase-related protein-1 in B16 mouse melanoma cells

Biochem J. 1999 Dec 15;344 Pt 3(Pt 3):659-65.


Tyrosinase and tyrosinase-related protein-1 (TRP-1) are two melanogenic enzymes that regulate melanin biosynthesis. Both are glycoproteins and belong to the TRP-1 gene family. They share a significant level of sequence similarity in several regions, including the catalytic domain and the potential N-glycosylation sites. We have recently shown that inhibition of the early steps of N-glycan processing in B16F1 cells dramatically affects tyrosinase activity and melanin synthesis. We present here results on N-glycan processing of TRP-1 and tyrosinase and compare the maturation process and activity of both glycoproteins in the presence of inhibitors of the endoplasmic reticulum stages of N-glycosylation. N-glycan analysis reveals that each of these two glycoproteins contains a mixture of high-mannose and sialylated complex N-glycans. However, in contrast to TRP-1, tyrosinase presents a homogeneous high-mannose glycoform, also. In the presence of alpha-glucosidases inhibitors, the maturation of tyrosinase N-glycans is completely inhibited, whereas TRP-1 is still able to acquire some complex glycans, indicating that endomannosidase acts preferentially on the later glycoprotein. In addition, the dopa-oxidase activity of tyrosinase is totally abolished, whereas for TRP-1 it is only partially affected. The results suggest that despite their structural similarity, tyrosinase is more sensitive than TRP-1 to perturbations of early N-glycan processing, in terms of maturation and catalytical activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 1-Deoxynojirimycin / analogs & derivatives
  • 1-Deoxynojirimycin / pharmacology
  • Amidohydrolases / metabolism
  • Animals
  • Glycoside Hydrolases / antagonists & inhibitors
  • Glycoside Hydrolases / metabolism
  • Glycosylation
  • Hexosaminidases / metabolism
  • Membrane Glycoproteins*
  • Mice
  • Monophenol Monooxygenase / metabolism*
  • Oligosaccharides / analysis
  • Oxidoreductases*
  • Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase
  • Polysaccharides / chemistry
  • Proteins / metabolism*
  • Tumor Cells, Cultured


  • Membrane Glycoproteins
  • Oligosaccharides
  • Polysaccharides
  • Proteins
  • 1-Deoxynojirimycin
  • miglustat
  • Oxidoreductases
  • Tyrp1 protein, mouse
  • tyrosinase-related protein-1
  • Monophenol Monooxygenase
  • Glycoside Hydrolases
  • Hexosaminidases
  • Amidohydrolases
  • Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase