This gene encodes a capillary endothelial cell protein that facilitates the lipolytic processing of triglyceride-rich lipoproteins. The encoded protein is a glycosylphosphatidylinositol-anchored protein that is a member of the lymphocyte antigen 6 (Ly6) family. This protein plays a major role in transporting lipoprotein lipase (LPL) from the subendothelial spaces to the capillary lumen. Mutations in this gene are the cause of hyperlipoproteinemia, type 1D. Alternate splicing results in multiple transcript variants. [provided by RefSeq, Sep 2014]