Protein half-lives of two subunits of an NMDA receptor-like complex, the 71-kDa glutamate-binding and the 80-kDa CPP-binding protein.
We determined the half-lives for two subunits of a complex that functions as a glutamate and N-methyl-D-aspartate (NMDA) receptor-ion channel in synaptic membranes. These two proteins are a 71 kDa glutamate-binding protein (GBP) and an 80 kDa CPP-binding protein (CBP). Seven month-old Fischer 344 rats were injected with L-[14C] leucine. The radioactivity in the two proteins was determined in a crude synaptosomal membrane fraction obtained from the brains of rats sacrificed from 4 hours to 13 days after the injection. The previously reported data on time-dependent appearance and loss of L-[14C] leucine radioactivity in the serum (Ferrington et al., 1997, Biochem. Biophys. Res. Commun. 237, 163-165) was used in the present study to estimate the half-lives of GBP and CBP. Theoretical curves best fit the experimental data obtained for the two proteins assuming apparent half-lives of 14 (+/- 2.4) and 18 (+/- 1.2) hours for CBP and GBP, respectively.
Chen
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Department of Pharmacology and Toxicology, University of Kansas, Lawrence, Kansas 66045, USA.
Ferrington
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DA
Bigelow
D J
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Michaelis
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EK
D000818:Animals; D002250:Carbon Radioisotopes; D018698:Glutamic Acid / Q000378:metabolism*; D006207:Half-Life; D007425:Intracellular Membranes / Q000378:metabolism; D007930:Leucine / Q000378:metabolism; D046911:Macromolecular Substances; D008297:Male; D008970:Molecular Weight; D011865:Radioisotope Dilution Technique; D051381:Rats; D011916:Rats, Inbred F344; D017470:Receptors, Glutamate / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D016194:Receptors, N-Methyl-D-Aspartate / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism*; D013997:Time Factors
D002250:Carbon Radioisotopes; D046911:Macromolecular Substances; D017470:Receptors, Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; D007930:Leucine