Patent ID: 7981660

Claim:
A yeast or filamentous fungal host cell comprising a nucleic acid encoding a GlcNAc transferase I enzyme selected to have optimal activity in the ER or Golgi of said host cell, the enzyme comprising: (a) a GlcNAc transferase I catalytic domain having optimal activity in said endoplasmatic reticulum (ER) or Golgi at a pH between 5.1 and 8.0; fused to (b) a cellular targeting signal peptide not normally associated with the catalytic domain selected to target the GlcNAc transferase I catalytic domain to the ER or Golgi apparatus of the host cell, wherein said host cell is capable of producing recombinant glycoproteins wherein an excess of 30 mole % of the N-glycan structures attached thereto have a Man 5 GlcNAc 2 , structure that can serve as a substrate for GlcNAc transferase I in vivo.