title: Presence of sulfated proteoglycans in prolactin secretory granules isolated from the rat pituitary gland.
abstract: The composition of the segregated content of rat prolactin granules was investigated taking advantage of the fact that these organelles, isolated as a pure fraction, retain their structural organization after solubilization of their limiting membrane by mild detergent treatment. We found that these membraneless granules contain not only the hormone, but also a number of minor macromolecular components including sulfated glycosaminoglycans, which are labeled when pituitary slices are incubated in vitro with [35S] sulfate. In order to characterize the latter components, the isolated radioactive granules were solubilized (by treatment with either a high ionic strength solution orNaOH) and 35S-labeled acidic glycosaminoglycans precipitated by complexing with cetylpirydinium chloride. A high degree of heterogeneity was observed when the ensuing precipitates were analyzed by cellulose acetate electrophoresis: different components were found to co-migrate with authentic heparin and chondroitin sulfate A and C standards. Another component, which accounts for approx. 50% of the glycosaminoglycan-bound radioactivity, might be heparin sulfate. These acidic glycosaminoglycans are linked to peptide moieties to form proteoglycans.
mesh_terms: D000818:Animals; D003594:Cytoplasmic Granules / Q000378:metabolism*; D004588:Electrophoresis, Cellulose Acetate; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006025:Glycosaminoglycans / Q000378:metabolism; D006595:Hexosamines / Q000032:analysis; D006601:Hexoses / Q000032:analysis; D066298:In Vitro Techniques; D008566:Membranes / Q000378:metabolism; D010902:Pituitary Gland / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D011509:Proteoglycans / Q000378:metabolism; D051381:Rats; D012794:Sialic Acids / Q000032:analysis; D013464:Sulfuric Acids / Q000032:analysis; D014574:Uronic Acids / Q000032:analysis
chemical_list: D006025:Glycosaminoglycans; D006595:Hexosamines; D006601:Hexoses; D011509:Proteoglycans; D012794:Sialic Acids; D013464:Sulfuric Acids; D014574:Uronic Acids; D011388:Prolactin