Effect of extracellular pH, ammonia, and cell aggregation on the specific expression rate and N-linked glycosylation of recombinant mouse-placental lactogen proteins by Chinese hamster ovary (CHO) cells

xperiments were performed using recombinant, anchorage-dependent Chinese hamster ovary (CHO) cells expressing either the glycosylated recombinant protein mouse placental lactogen-I (mPL-I) or the unglycosylated recombinant protein mouse placental lactogen-II (mPL-II). The mPL-I or mPL-II cDNA was co-amplified with DHFR by methotrexate selection in CHO cells.;Glycosylation patterns and specific expression rates of the recombinant protein mPL-I by CHO cells under non-growth conditions in serum-free, protein expression medium varied significantly over the extracellular pH (pH;The N-linked glycosylation of mPL-I by Chinese hamster ovary (CHO) cell T-flask cultures under non-growth conditions was inhibited by increasing levels of ammonium chloride (3 and 9 mM) in the serum-free, protein expression medium. The effect of ammonia on glycosylation was dependent on the pH;There was preliminary evidence that expression of lower molecular sized mPL-I glycoforms by CHO cells increased from a microcarrier culture with cell aggregates with sizes up to 600...