Schematic illustration of the multidomain structure of human Pln. The core protein of Pln consists of five domains I–V [194]. Domain I is made up of a sperm, enterokinase and agrin (SEA) fold, preceded by three GAG attachment sites. Domain II contains four low-density lipoprotein (LDL) receptor motifs and one isolated immunoglobulin-like (Ig) fold. Domain III is made up of a combination of laminin epidermal growth factor (EGF) and laminin IV type A domains that are connected by disulfide linkages in the laminin EGF domains to form an inflexible rod-like structure. In humans, domain IV consists of 21 repeating Ig C2-type modules that are sequentially linked together. Domain V comprises four EGF motifs, three laminin G, and a fourth variable GAG attachment site.