The function of PLTP (phospholipid transfer protein, Ensembl gene identifier ENSG00000100979) is as follows. Mediates the transfer of phospholipids and free cholesterol from triglyceride-rich lipoproteins (low density lipoproteins or LDL and very low density lipoproteins or VLDL) into high-density lipoproteins (HDL) as well as the exchange of phospholipids between triglyceride-rich lipoproteins themselves (PubMed:11013307, PubMed:19321130, PubMed:21515415, PubMed:29883800, PubMed:7654777, PubMed:9132017). Facilitates the transfer of a spectrum of different lipid molecules, including diacylglycerol, phosphatidic acid, sphingomyelin, phosphatidylcholine, phosphatidylinositol, phosphatidylglycerol, cerebroside and phosphatidyl ethanolamine (PubMed:9132017). Plays an important role in HDL remodeling which involves modulating the size and composition of HDL (PubMed:29883800). Also plays a key role in the uptake of cholesterol from peripheral cells and tissues that is subsequently transported to the liver for degradation and excretion (PubMed:21736953). Two distinct forms of PLTP exist in plasma: an active form that can transfer phosphatidylcholine from phospholipid vesicles to HDL, and an inactive form that lacks this capability (PubMed:11013307). {ECO:0000269|PubMed:11013307, ECO:0000269|PubMed:19321130, ECO:0000269|PubMed:21515415, ECO:0000269|PubMed:29883800, ECO:0000269|PubMed:7654777, ECO:0000269|PubMed:9132017, ECO:0000303|PubMed:21736953}.