Two new crops in the biotech harvest.

Two new crops in the biotech harvest

Biotechnology continues to provide biologists and medical researchers with crucial materials that are too scarce in the body to be isolated for laboratory study. This month, Integrated Genetics of Framingham, Mass., announced the successful production in bacteria of human protein C, an anticoagulant important in regulating the clotting process. And at the University of California at San Francisco (UCSF), scientists have used genetically engineered bacteria to produce apolipoprotein (apo-E), which is involved in cholesterol metabolism. The UCSF work was reported in the December (No. 24) PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES.

Protein C plays a key role in mediating blood clot formation and dissolution (SN: 1/26/85, p. 54). The protein both inactivates coagulation cofactors 5 and 8c and facilitates the breakdown of clots by stimulating tissue plasminogen activator (t-PA), a clot-dissolving substance. Integrated Genetics expects that protein C produced with genetic engineering will be useful for treating patients at risk of clotting problems due to acquired and congenital protein C deficiencies. The company also expects the protein to serve as an adjunct to t-PA for the treatment of cardiovascular patients. According to spokesperson Pat Connoy, the company plans to begin clinical evaluations of protein C in one year and hopes the protein will be available as a therapeutic agent in three years.

The recent production of apo-E by UCSF genetic engineering scientists in conjunction with Bio-Technology General Ltd. of Israel is expected to provide researchers with abundant quantities of the substance for studies of cholesterol metabolism. The apo-E protein facilitates the binding of cholesterol-carrying lipoproteins to receptors on the cell surface, speeding the removal of cholesterol from the blood.

According to Robert W. Mahley of UCSF, the cloning of apo-E protein could have two important consequences. Through a process called site-specific mutagenesis, amino acids within the protein can be changed; analysis of the altered protein would provide researchers with a better understanding of how apo-E interacts with cell receptors. Secondly, researchers can now infuse large quantities of apo-E into animals. Mahley speculates that this treatment may accelerate removal of cholesterol by the liver, and thus reduce the deposit of cholesterol on artery walls, lowering incidence of heart attacks.