Milk Protein Typing of Bovine Mammary Gland Tissue Used to Generate a Complementary Deoxyribonucleic Acid Library

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Abstract
The milk protein genotype of a mammary gland tissue that was used to generate a cDNA library at the University of California. Davis was typed by PAGE. Casein and whey proteins were extracted from the mammary tissue and typed utilizing fast mini-gel procedures that provide excellent resolution of the milk proteins. The genotype of the mammary tissue was classified as .kappa.-casein AB, .beta.-casein A2A1, .alpha.s1-casein BB, .beta.-lactoglobulin AA, and .alpha.-lactalbumin BB. The genes .kappa.-casein A, .beta.-casein A2, .beta.-lactoglobulin A, and .alpha.-lactalbumin B that have been cloned from this cDNA library coincide with those in the above tissue genotype with the exception of the recently reported cloning of the .alpha.s1-casein A gene. The gene frequencies for the casein genetic variants for three breeds of dairy cattle is presented and discussed in relation to the low frequency (.3%) of the .alpha.s1-casein A in the population.