Protein production in the milk of genetically engineered animals

There are numerous proteins that have potential commercial and scientific applications that are not fully utilized due to limitations of current isolation methods. The purpose of this research was to target recombinant protein expression to the mammary glands of transgenic animals.To test this approach for protein production, expression vectors for two different plant proteins were made. The proteins targeted for expression were thaumatin and brazzein, which have sweetener or flavor altering properties. The regulatory portion of the expression vector used sequences from the milk b -casein and alpha S-1 casein genes. The plant protein sequence was modified by using codons commonly used for casein and generated using synthetic oligonucleotides. The DNA expression vectors were injected into murine and caprine embryos for the production of transgenic animal. Transgenic mice and a goat were identified that contained the thaumatin transgene. Preliminary analysis of mouse milk by capillary electrophoresis indicated thaumatin protein expression.