Arabidopsis is often used as a model organism to study expression in plants, while actual production may be carried out in maize, rice, potatoes, tobacco, flax or safflower. The advantage of rice and flax is that they are self-pollinating, and thus gene flow issues (see below) are avoided. However, human error could still result in pharm crops entering the food supply. Using a minor crop such as safflower, or a non-food crop such as tobacco, avoids the greater political pressures and risk to the food supply involved with using staple crops such as maize or rice.

 

Expression in the milk of a mammal, such as a cow, sheep, or goat, is a common application, as milk production is plentiful and purification from milk is relatively easy. Hamsters and Rabbits have also been used in preliminary studies because of their faster breeding.

One potential approach to this technology is the creation of a transgenic mammal that can produce the biopharmaceutical in its milk (or blood or urine). Once an animal is produced, typically using the pronuclear microinjection method, it becomes efficacious to use cloning technology to create additional offspring that carry the favorable modified genome.^[1] The first such drug manufactured from the milk of a genetically-modified goat was ATryn®, but marketing permission was blocked by the European Medicines Agency in February 2006.^[2] This decision was reversed in June 2006 and approval was given August 2006.^[3]

 

به سبب اینکه ماکرومولکول های زیستی مانند دی‌ان‌ای و پروتئین ها باردار هستند می‌‌توان با قرار دادن آنها در یک میدان الکتریکی، آنها را بر اساس خواص فیزیکی مانند شکل فضایی، وزن مولکولی و بار الکتریکی، تفکیک کرد. برای این منظور از روشی بنام الکتروفورز استفاده می‌‌شود. روش های مختلف الکتروفورزی برای تفکیک و مطالعه بیومولکول ها اعم از اسید های نوکلئیک یا پروتئین ها ابداع شده است.