title: Yolk granules are the major compartment for bullfrog (Rana catesbeiana) oocyte-specific ribonuclease.
abstract: Rana catesbeiana ribonuclease (RC-RNase) is a pyrimidine guanine sequence-specific ribonuclease found only in R. catesbeiana (bullfrog) oocytes, not in other organs. An immunohistochemical assay showed that RC-RNase was present in the regular yolk granules, but not in forming yolk granules, yolk platelets, pigment granules, mitochondria clouds or the nucleus. The RC-RNase was restricted to the lateral amorphous area of the yolk granules, and was absent from the central area that has a vitellogenin crystal lattice. The RC-RNase was extracted from yolk granules by 0.5 M NaCl and purified by dialysis and affinity chromatography. Most of the RC-RNase (94%) was found in the yolk granules, the rest RC-RNase (6%) was found in the cytosol in the form of free RNase and latent RNase. The RC-RNase extracted from yolk granules was further analyzed by immunoprecipitation and RNase activity assay on an SDS/polyacrylamide gel. Our results suggest that the RC-RNase activity is regulated by both compartmentation and inhibitor binding.
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan, ROC.
authors.forename: Y D
authors.initials: YD
authors.lastname: Liao
authors.forename: J J
authors.initials: JJ
authors.lastname: Wang
mesh_terms: D000818:Animals; D002451:Cell Compartmentation; D004530:Egg Yolk / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D009865:Oocytes / Q000201:enzymology*; D011233:Precipitin Tests; D011892:Rana catesbeiana; D012260:Ribonucleases / Q000302:isolation & purification / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D012260:Ribonucleases