PMC:3248852 / 12668-15400 JSONTXT

{"target":"https://pubannotation.org/docs/sourcedb/PMC/sourceid/3248852","sourcedb":"PMC","sourceid":"3248852","source_url":"http://www.ncbi.nlm.nih.gov/pmc/3248852","text":"Progesterone stimulation of protein phosphorylation in Rana oocytes\nThe upper panel of Figure 6 compares 32PO4 uptake from the medium by control and progesterone-treated Rana ovarian follicles, expressed as moles/liter of oocyte water. Extracellular inorganic PO4 levels were maintained at 80 μM. Uptake was essentially identical in control and progesterone-treated oocytes during the first 5 h, but markedly increased in progesterone-treated oocytes prior to the onset of nuclear membrane breakdown, continuing to rise even after completion of the membrane dissolution. The lower panel of Figure 6 compares 32PO4 incorporation into the TCA precipitable components of the control and progesterone-treated oocytes shown in the upper panel. In progesterone-treated oocytes, 13 ± 2% (N = 3) of the total 32PO4 taken up is incorporated into total protein, phospholipid and nucleic acid components by completion of nuclear membrane breakdown, compared to 5 ± 1% (N = 3) incorporation in control oocytes over the same time period.\nFigure 6 Comparison of 32PO4 uptake by control and progesterone-treated Rana pipiens ovarian follicles. Upper panel: in-vitro [32PO4] uptake by control and progesterone-treated denuded oocytes. Oocytes were incubated in Ringers' solution containing 0.08 mM NaHPO4 and 32PO4 uptake is expressed as μmols/1 cell water. Lower panel: oocytes from the upper panel were homogenized in 7% TCA and protein isolated as described in Methods. 32PO4 uptake into total protein is expressed as μmols/kg wet weight. Since the major increase in protein phosphorylation occurred after 4 - 6 h exposure to inducing levels of progesterone (Figure 6), isolated follicles were preincubated in Ringer's solution containing 3.2 μM progesterone for 5 h, then pulse labeled with Ringer's solution containing 32PO4 and 3.2 μM progesterone for 4 h. The oocytes were rinsed, homogenized at ice-bath temperatures and phosvitin isolated as described in Methods. Table 1 compares 32PO4 uptake into purified phosvitin in control and progesterone-stimulated follicles. A 15 fold increase in 32PO4 incorporation was observed in phosvitin isolated from progesterone-treated follicles. Compared to the controls, 3.2 μM progesterone produced a 22 ± 4% (N = 3) increase in phosvitin phosphate, based on phosphate analysis [5].\nTable 1 Comparison of [32PO4] Incorporation into Purified Phosvitin from Control and Progesterone-treated Rana pipiens Folliclesa aIsolated ovarian follicles were preincubated in Ringer's solution with or without 3.2 jaU progesterone for 5 h at 22°C, [32PO4] added, and then further incubated for 4 h. bMean ± SD (N = 3) Denuded oocytes and/or isolated ovarian follicles from 3 hibernating Rana pipiens females.\n\n","divisions":[{"label":"Title","span":{"begin":0,"end":67}},{"label":"Figure caption","span":{"begin":1025,"end":1528}},{"label":"Table caption","span":{"begin":2317,"end":2731}}],"tracks":[{"project":"2_test","denotations":[{"id":"22054214-4558563-9450417","span":{"begin":2313,"end":2314},"obj":"4558563"}],"attributes":[{"subj":"22054214-4558563-9450417","pred":"source","obj":"2_test"}]}],"config":{"attribute types":[{"pred":"source","value type":"selection","values":[{"id":"2_test","color":"#ec93ec","default":true}]}]}}