Inside-outside distribution and diffusion of phosphatidylcholine in rat sarcoplasmic reticulum as determined by 13C NMR and phosphatidylcholine exchange protein
Publication date
1979-08-07
Authors
Kruijff, B. de
Besselaar, A.M.H.P. van den
Bosch, H. van den
Deenen, L.L.M. van
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Article
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Abstract
1. 1. The transverse distribution of phosphatidylcholine in rat sarcoplasmic reticulum was investigated employing 13C NMR in conjunction with the shift reagent DyCl3.
2. 2. Sarcoplasmic reticulum phosphatidylcholine was enriched with 13C by feeding rats a diet containing [N-Me3-13C]choline. Up to 32% of the sarcoplasmic reticulum phosphatidyl-[N-Me3-12C]choline was replaced by phosphatidyl-[N-Me3-13C]choline.
3. 3. Titration of 13C-enriched sarcoplasmic reticulum with Dy3+ indicates that 40% of the phosphatidyl-[N-Me3-13C]choline is exposed to the external medium, whereas 60% is shielded from interaction with Dy3+.
4. 4. Incubation of 32P-labelled sarcoplasmic reticulum with excess mitochondria and phosphatidylcholine exchange protein results in a fast transport of approx. 80% of [32P]phosphatidylcholine to the mitochondria indicating that part of the phosphatidylcholine pool is involved in a rapid transbilayer movement.
Keywords
13C-NMR, exchange protein, phosphatidylcholine, transbilayer movement, sarcoplasmic reticulum membrane