Proteins iodinated by the chloramine-T method appear to be degraded at an abnormally rapid rate after endocytosis

Journal Article · Sat Mar 01 00:00:00 EST 1980 · Proc. Natl. Acad. Sci. U.S.A.; (United States)

DOI:https://doi.org/10.1073/pnas.77.3.1556· OSTI ID:6695906

Opresko, L; Wiley, H S; Wallace, R A

Proteins labeled with either /sup 3/H by reductive methylation or /sup 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, /sup 125/I-labeled proteins were apparently degraded at rates far exceeding their /sup 3/H-labeled counterparts, based on the generation of acid-soluble radioactivity. Thus, after a 3-hr incubation, 3 to 5 times more /sup 125/I-labeled bovine serum albumin and X. laevis serum proteins lacking albumin were degraded than the corresponding /sup 3/H-labeled proteins (95% compared to 30% and 75% compared to 15%, respectively), whereas after a 24-hr incubation, the degradation of /sup 125/I-labeled vitellogenin was 15 times greater than that of (/sup 3/H)vitellogenin labeled in vivo (60% compared to 4%). Moreover, examination of the relative amounts of /sup 3/H-compared to /sup 125/I-labeled bovine serum albumin deposited into the exogenously derived yolk platelet compartment of the oocyte revealed 7 times more acid-precipitable /sup 3/H-labeled protein, indicating that the observed discrepancies were not due to reincorporation of the /sup 3/H-labeled ligands. Passage of dissolved oocytes previously exposed to /sup 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 (approx. = 90%) of labeled low molecular weight compounds, which analysis showed to be 72% free iodine.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 6695906
• Journal Information: Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 77:3
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
62 RADIOLOGY AND NUCLEAR MEDICINE
ALBUMINS
IODINATION
LABELLING
SIDE EFFECTS
BIOCHEMICAL REACTION KINETICS
CHEMICAL PROPERTIES
COMPARATIVE EVALUATIONS
DECOMPOSITION
IODINE 125
LABELLED COMPOUNDS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
BETA DECAY RADIOISOTOPES
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
ELECTRON CAPTURE RADIOISOTOPES
HALOGENATION
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PROTEINS
RADIOISOTOPES
REACTION KINETICS
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