MGAT1 deficient cells and uses thereof

A method for producing a glycoprotein, the method comprising:

• obtaining a mannosyl (alpha-1,3-)-glycoprotein beta-1,2-N-acetylglucosaminyltransferase-deficient (MGAT1-deficient) cell, wherein the MGAT1-deficient cell comprises in its genome SEQ ID NO:
• 6 and is produced by a method comprising:
• introducing into a parent cell an RNA-guided endonuclease together with a guide RNA (gRNA) comprising a sequence as set forth in
• (SEQ ID NO:
• 2)
• GGAUGCGCAGACCUGAGCAG,
• (SEQ ID NO:
• 3)
• GGUAGUGGAGGACGAUCUGG,
• (SEQ ID NO:
• 4)
• UUUCUCCACCUGUAGCAGGG, or
• (SEQ ID NO:
• 5)
• GAUCGCCAGGCACUACCGCU;
• culturing the parent cell and expanding the parent cell;
• isolating a plurality of daughter cells from the cell culture;
• identifying a modified cell deficient in MGAT1 activity;
• and
• isolating said modified cell deficient in MGAT1 activity;
• expressing in the MGAT1-deficient cell a protein having an N-glycosylation site, whereby the protein is an Nonglycosylated protein that is N-glycosylated at the N-glycosylation site with an oligomannose glycan;
• and
• isolating the N-glycosylated protein from the cell.