Description:
AbstractMammary‐derived growth inhibitor (MDGI), a polypeptide growth inhibitor isolated from lactating bovine mammary tissue, previously shown to have extensive sequence homology with fatty acid‐binding proteins, was demonstrated to meet the criteria of a fatty acid‐binding protein. The protein was found to bind [3H]palmitic acid in a saturable manner and to be complexed with endogeneous free fatty acids. [3H]palmitic acid, when bound to the protein, was more rapidly taken up by the target cells (human mammary carcinoma cells [MaTu]) than was free [3H]palmitic acid, suggesting a lipid carrier function for the inhibitor. It is suggested that the fatty acid‐binding properties of MDGI may relate to its ability to inhibit cell growth in vitro and to regulate other cellular functions.