title: Dermatan sulphate-rich proteoglycan associates with rat tail-tendon collagen at the d band in the gap region.
abstract: Rat tail tendon was stained with a cationic phthalocyanin dye, Cupromeronic Blue, in a 'critical-electrolyte-concentration' method [Scott (1980) Biochem. J. 187, 887-891] specifically to demonstrate proteoglycan by electron microscopy. Hyaluronidase digestion in the presence of proteinase inhibitors corroborated the results. Collagen was stained with uranyl acetate and/or phosphotungstic acid to demonstrate the banding pattern a-e in the D period. Proteoglycan was distributed about the collagen fibrils in an orthogonal array, the transverse elements of which were located almost exclusively at the d band, in the gap zone. The proteoglycan may inhibit (1) fibril radial growth by accretion of collagen molecules or fibril fusion, through interference with cross-linking, and (2) calcification by occupying the holes in the gap region later to be filled with hydroxyapatite.
mesh_terms: D000818:Animals; D003094:Collagen / Q000378:metabolism*; D003871:Dermatan Sulfate / Q000378:metabolism; D006651:Histocytochemistry; D006821:Hyaluronoglucosaminidase / Q000378:metabolism; D007211:Indoles; D008854:Microscopy, Electron; D009942:Organometallic Compounds; D011509:Proteoglycans / Q000378:metabolism*; D051381:Rats; D013710:Tendons / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D007211:Indoles; D009942:Organometallic Compounds; D011509:Proteoglycans; D003871:Dermatan Sulfate; C015445:copper phthalocyanine; D003094:Collagen; D006821:Hyaluronoglucosaminidase