Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Proteins iodinated by the chloramine-T method appear to be degraded at an abnormally rapid rate after endocytosis.
Opresko L
,
Wiley HS
,
Wallace RA
.
Abstract
Proteins labeled with either (3)H by reductive methylation or (125)I by the chloramine-T method were incubated with Xenopus laevis oocytes; the incorporation and acid precipitability of the proteins were then studied. The uptake rates of both specifically incorporated (vitellogenin) and nonspecifically incorporated proteins (bovine serum albumin and X. laevis serum proteins lacking albumin) were not influenced by the method of labeling. However, (125)I-labeled proteins were apparently degraded at rates far exceeding their (3)H-labeled counterparts, based on the generation of acid-soluble radioactivity. Thus, after a 3-hr incubation, 3-5 times more (125)I-labeled bovine serum albumin and X. laevis serum proteins lacking albumin were degraded than the corresponding (3)H-labeled proteins (95% compared to 30% and 75% compared to 15%, respectively), whereas after a 24-hr incubation, the degradation of (125)I-labeled vitellogenin was 15 times greater than that of [(3)H]vitellogenin labeled in vivo (60% compared to 4%). Moreover, examination of the relative amounts of (3)H- compared to (125)I-labeled bovine serum albumin deposited into the exogenously derived yolk platelet compartment of the oocyte revealed 7 times more acid-precipitable (3)H-labeled protein, indicating that the observed discrepancies were not due to reincorporation of the (3)H-labeled ligands. Passage of dissolved oocytes previously exposed to (125)I-labeled bovine serum albumin (chloramine-T method) over a column of Bio-Gel P-10 revealed some breakdown of bovine serum albumin to intermediate molecular weight components and the presence of a large amount ( approximately 90%) of labeled low molecular weight compounds, which analysis showed to be 72% free iodine. The evolution of either iodotyrosine or free iodine would nevertheless be perceived as protein degradation by most analytical procedures (e.g., acid precipitation or autoradiography). We conclude, therefore, that apparent degradation rates observed for endocytotically incorporated proteins may vary depending on the method used to label the protein and caution should be exercised when interpreting results obtained with labeled, particularly chloramine-T labeled, proteins.
Ascoli,
Tritium labeling of luteinizing hormone by reductive methylation.
1974, Pubmed
Ascoli,
Tritium labeling of luteinizing hormone by reductive methylation.
1974,
Pubmed
Bramhall,
A simple colorimetric method for determination of protein.
1969,
Pubmed
Carpenter,
125I-labeled human epidermal growth factor. Binding, internalization, and degradation in human fibroblasts.
1976,
Pubmed
DAVIS,
DISC ELECTROPHORESIS. II. METHOD AND APPLICATION TO HUMAN SERUM PROTEINS.
1964,
Pubmed
GREENWOOD,
THE PREPARATION OF I-131-LABELLED HUMAN GROWTH HORMONE OF HIGH SPECIFIC RADIOACTIVITY.
1963,
Pubmed
Goldstein,
Binding and degradation of low density lipoproteins by cultured human fibroblasts. Comparison of cells from a normal subject and from a patient with homozygous familial hypercholesterolemia.
1974,
Pubmed
Gorden,
Intracellular translocation of iodine-125-labeled insulin: direct demonstration in isolated hepatocytes.
1978,
Pubmed
Haigler,
Visualization by fluorescence of the binding and internalization of epidermal growth factor in human carcinoma cells A-431.
1978,
Pubmed
Jared,
Distribution of incorporated and synthesized protein among cell fractions of Xenopus oocytes.
1973,
Pubmed
,
Xenbase
Lee,
Interaction of ovarian receptors with human luteinizing hormone and human chorionic gonadotropin.
1973,
Pubmed
ORNSTEIN,
DISC ELECTROPHORESIS. I. BACKGROUND AND THEORY.
1964,
Pubmed
Ohlendorf,
Lipid and polypeptide components of the crystalline yolk system from Xenopus laevis.
1977,
Pubmed
,
Xenbase
Opresko,
The origin of yolk-DNA in Xenopus laevis.
1979,
Pubmed
,
Xenbase
Rodbard,
Estimation of molecular radius, free mobility, and valence using polyacylamide gel electrophoresis.
1971,
Pubmed
Roth,
Peptide hormone binding to receptors: a review of direct studies in vitro.
1973,
Pubmed
Sapira,
Chromatography of aromatic amino acid derivatives on polyamide thin layers.
1969,
Pubmed
Terris,
Binding and degradation of 125I-insulin by rat hepatocytes.
1975,
Pubmed
Terris,
Retention and degradation of 125I-insulin by perfused livers from diabetic rats.
1976,
Pubmed
Wallace,
Studies on amphibian yolk. VII. Serum phosphoprotein synthesis by vitellogenic females and estrogen-treated males of Xenopus laevis.
1968,
Pubmed
,
Xenbase
Wallace,
Studies on amphibian yolk. 8. The estrogen-induced hepatic synthesis of a serum lipophosphoprotein and its selective uptake by the ovary and trasformation into yolk platelet proteins in Xenopus laevis.
1969,
Pubmed
,
Xenbase
Wallace,
Protein incorporation by isolated amphibian oocytes. I. Preliminary studies.
1970,
Pubmed
Wallace,
Studies on amphibian yolk. IX. Xenopus vitellogenin.
1970,
Pubmed
,
Xenbase
Wallace,
Studies on amphibian yolk. X. The relative roles of autosynthetic and heterosynthetic processes during yolk protein assembly by isolated oocytes.
1972,
Pubmed
,
Xenbase
Wallace,
Protein incorporation by isolated amphibian oocytes. 3. Optimum incubation conditions.
1973,
Pubmed
,
Xenbase
Wallace,
Protein incorporation by isolated amphibian oocytes. V. Specificity for vitellogenin incorporation.
1976,
Pubmed
,
Xenbase
Wallace,
Long-term growth and differentiation of Xenopus oocytes in a defined medium.
1978,
Pubmed
,
Xenbase
Wallace,
Turnover of endogenous, microinjected, and sequestered protein in Xenopus oocytes.
1979,
Pubmed
,
Xenbase
Wiley,
New methods for the purification of vertebrate vitellogenin.
1979,
Pubmed
,
Xenbase
Wille,
A simple and rapid method for isolation of serum lipoproteins from the other serum protein constituents.
1976,
Pubmed
Williams,
Quantitative studies of pinocytosis. II. Kinetics of protein uptake and digestion by rat yolk sac cultured in vitro.
1975,
Pubmed
Willinger,
Fate of surface proteins of rabbit polymorphonuclear leukocytes during phagocytosis. II. Internalization of proteins.
1979,
Pubmed
Wyckoff,
Polyacrylamide gel electrophoresis in sodium dodecyl sulfate-containing buffers using multiphasic buffer systems: properties of the stack, valid Rf- measurement, and optimized procedure.
1977,
Pubmed
