Cloning, yeast expression, purification and biological activity of the extension region of the soybean 7S globulin alfa’ subunit involved in Hep G2 cell cholesterol homeostasis

A truncated form of a' chain (ea'), the soybean 7S globulin, active in controlling the cholesterol and triglyceride homeostasis in in vitro and in vivo models, was cloned and expressed in the yeast Pichia pastoris. The recombinant polypeptide spanned 142 amino acid residues from the N-terminal side and included the N-terminal extension region of the soybean alpha' subunit. The ea' polypeptide was purified by conventional biochemical techniques and its potential to modulate the activity of the LDL-receptor was evaluated in a human hepatoma cell line (Hep G2) by monitoring the uptake and degradation of labeled LDL.