The function of BLTP1 (bridge-like lipid transfer protein family member 1, ENSG00000138688) is as follows. Bridge-like lipid transfer protein that functions as molecular bridges between endoplasmic reticulum and the membranes targeted for lipid delivery (PubMed:35491307, PubMed:40269155). Forms a tunnel with multiple beta-grooves that allows the transport of phospholipids (By similarity). Provides phosphatidylethanolamine for glycosylphosphatidylinositol (GPI) anchor synthesis in the endoplasmic reticulum (PubMed:35015055). Plays a role in endosomal trafficking and endosome recycling (PubMed:30906834). Also involved in the actin cytoskeleton and cilia structural dynamics (PubMed:30906834). Acts as a regulator of phagocytosis (PubMed:31540829). Required for the formation of endoplasmic reticulum-plasma membrane junctions which are critical for lipid exchange (PubMed:40269155). {ECO:0000250|UniProtKB:A0A0K3AWP8, ECO:0000269|PubMed:30906834, ECO:0000269|PubMed:31540829, ECO:0000269|PubMed:40269155, ECO:0000305|PubMed:35015055, ECO:0000305|PubMed:35491307}.