The functional and regulatory entities underlying free and peptide-bound amino acid transporters in the bovine mammary gland

Abstract

Graphical Abstract Summary: Milk produced from the mammary glands of dairy animals has been recognized as a vital source of high-quality protein for human consumption. In addition to the common form, free amino acids (AA) absorbed from blood as predominant precursors for milk protein synthesis, peptide-bound AA transported by multiple transport systems into mammary epithelial cells also facilitate milk protein production. Here we summarized the expanding knowledge about how the 2 different AA transporter systems contribute to mammary AA utilization for milk protein synthesis as well as the major mTORC1-S6K1-4EBP1-mediated regulatory mechanism in the context of lactation. Such knowledge possibly provides insights into the feeding strategies of improving milk protein production in dairy animals.