Basement membrane-associated chondroitin sulfate proteoglycan (CSPG). Has prolyl 3-hydroxylase activity catalyzing the post-translational formation of 3-hydroxyproline in -Xaa-Pro-Gly- sequences in collagens, especially types IV and V. May be involved in the secretory pathway of cells. Has growth suppressive activity in fibroblasts (By similarity). 2-oxoglutarate + L-prolyl-[collagen] + O2 = CO2 + succinate + trans-3-hydroxy-L-prolyl-[collagen] Secreted into the extracellular matrix as a chondroitin sulfate proteoglycan (CSPG). Expressed in basement membranes of cardiac muscle, skeletal muscle, central nervous system, intestinal tract, trachea, ear, skin, liver and kidney. In kidney, localizes to the glomerular basement membrane, mesangial matrix and Bowman's capsule of the nephron. In the renal parenchyma, expressed in the basement membranes of tubules and blood vessels. In the ear and trachea, localizes to the perimeter of resident chondrocytes in lacunae. O-glycosylated; chondroitin sulfate. Belongs to the leprecan family.