Vitamin D3 action on D,L-serine-3-14C incorporation into phospholipid fractions with rat liver mitochondria.

Abstract

Calcium activated biosynthesis of phospholipids was studied with liver mitochondria, inner and outer membranes obtained from vitamin D deficient and vitamin D3 fed rats. Calcium activated D, L-serine-3-14C incorporation into phospholipids was observed at 37°, but did not occur at 4°. This reached maximum during the first 30min, and the optimal calcium concentration was 12mM. The inhibitors, such as cyanide, 2, 4-dinitrophenol, arsenate and oligomycin had no effect on the serine incorporation. N-ethylmaleimide had inhibitory effect. 45Ca more easily binds to mitochondrial membrane in any incubational temperature. Calcium activated D, L-serine-3-14C incorporation into phospholipids was further stimulated by administration of vitamin D3 in rat liver mitochondria and outer membranes of mitochondria. The site of calcium activated biosynthesis of phospholipids was confined to outer membranes and the action of calcium was to expose its reaction center.From these results, it was recognized that vitamin D3 effect on calcium stimulated phospholipid synthesis was not on calcium uptake or binding, but more complexed reaction involved with phospholipid biosynthesis. It was also confirmed that vitamin D3 consisted in mitochondrial membrane, and concerned with transferring information or phospholipid precursors in the mitochondrial phospholipid biosynthesis.