Increase in intracellular calcium influx enhances monoclonal antibody productivity

摘要

The endoplasmic reticulumn (ER) is the site where not only the secretory and lysosomal proteins, resident luminal ER proteins, Golgi and lysosomal membrane proteins are synthesized, but most extensive folding, and oligomeric assembly take place (Gething and Sambrook, 1192; Hurtley and Helenius, 1989). The ER is also a major intracellular reservoir of Ca~(2+) and serves as a major intracellular site of Ca~(2+) sequestration and is thought to function prominently in maintenance of Ca~(2+) homeostasis. The sequestered Ca~(2+) may function to maintain various proteins processing events within the ER. Although the exact concentration of Ca~(2+) in the ER is not known with certainty, measurement using electron probe X-ray microanalysis indicates that in different cells it can be between 1.8 and 5.4 mM. Meanwhile, the concentration of free (unbound) Ca~(2+) can be two or three orders of magnitude greater than the 1 #mu# M or lower concentration in the cytosol (Galina et al., 1993).