BOVINE BETA-CASEIN EXPRESSED IN TRANSGENIC MOUSE MILK IS PHOSPHORYLATED AND INCORPORATED INTO MICELLES

Transgenic mice carrying the bovine beta-casein gene linked to the pro moter sequence of the sheep beta-lactoglobulin milk protein gene were produced. Four of seven lines expressed the transgene protein with mic e from the two highest expressing lines producing 4 to 5 mg ml(-1) of this protein in their milk, The foreign protein was associated with th e casein micelles and did not segregate into the whey fraction on cent rifugation of milk samples, Following purification, the protein was ch aracterized by amino acid analysis, gel electrophoresis, capillary zon e electrophoresis, and trypsinolysis. The results showed that the tran sgene protein was authentic, phosphorylated bovine beta-casein A(1). ( C) 1996 Academic Press, Inc.