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Radiation inactivation was used to estimate the molecular size of a Na(+)-dependent amino acid transport system in Ehrlich ascites cell plasma membrane vesicles. Na(+)-dependent alpha-aminoisobutyric acid uptake was measured after membranes were irradiated at -78.5 degrees C in a cryoprotective medium. Twenty-five percent of the transport activity was lost at low radiation doses (less than 0.5 Mrad), suggesting the presence of a high molecular weight transport complex. The remaining activity (approximately 75% of total) decreased exponentially with increasing radiation dose, and a molecular size of 347 kDa was calculated for the latter carrier system. Vesicle permeability and intravesicular volume were measured to verify that losses in transport activity were due to a direct effect of radiation on the transporter and not through indirect effects on the structural integrity of membrane vesicles. Radiation doses 2-3-fold higher than those required to inactivate amino acid transport were needed to cause significant volume changes (greater than 15%). Vesicle permeability was unchanged by the irradiation. The structural integrity of plasma membrane vesicles was therefore maintained at radiation doses where there was a dramatic decrease in amino acid transport. The relationship between the fragmentation of a 120-130-kDa peptide, a putative component of the Na(+)-dependent amino acid carrier [McCormick, J. I., & Johnstone, R. M. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 7877-7881], and loss of transport activity in irradiated membranes was also examined. Peptide loss was quantitated by Western blot analysis.(ABSTRACT TRUNCATED AT 250 WORDS)
J I McCormick, and
M Jetté, and
M Potier, and
R Béliveau, and
R M Johnstone
March 1978,
The Journal of biological chemistry,
J I McCormick, and
M Jetté, and
M Potier, and
R Béliveau, and
R M Johnstone
January 1974,
The Journal of membrane biology,
J I McCormick, and
M Jetté, and
M Potier, and
R Béliveau, and
R M Johnstone
April 1988,
Biochemical and biophysical research communications,
J I McCormick, and
M Jetté, and
M Potier, and
R Béliveau, and
R M Johnstone
June 1988,
The Journal of biological chemistry,
J I McCormick, and
M Jetté, and
M Potier, and
R Béliveau, and
R M Johnstone
November 1988,
Proceedings of the National Academy of Sciences of the United States of America,
J I McCormick, and
M Jetté, and
M Potier, and
R Béliveau, and
R M Johnstone
January 1982,
Membrane biochemistry,
J I McCormick, and
M Jetté, and
M Potier, and
R Béliveau, and
R M Johnstone
February 1987,
Biochimica et biophysica acta,
J I McCormick, and
M Jetté, and
M Potier, and
R Béliveau, and
R M Johnstone
July 1968,
Radiation research,
J I McCormick, and
M Jetté, and
M Potier, and
R Béliveau, and
R M Johnstone
July 1982,
Biochimica et biophysica acta,
J I McCormick, and
M Jetté, and
M Potier, and
R Béliveau, and
R M Johnstone
May 1990,
Biochemistry,
