Intracellular and Intramitochondrial Distribution of Vitamin K : Biochemical and Electron Microscopic Radioautographic Study

Abstract

The intracellular distribution of vitamin K₁, K_{2 (20)} and K₃ in the rat liver and heart was studied by sucrose linear density gradient centrifugation and it was revealed that vitamin K₁ and K_{2 (20)} which have long alkyl side chain at 3-position of their common frame other than K₃ were incorporated in the mitochondria. This result was well consistent with the previous one which was obtained by differential centrifugation method. Further study of their intramitochondrial distribution revealed that they localized in the inner membrane of the mitochondria and some of them in the soluble fraction. Electron microscopic radioautography of ³H-vitamin K_{2 (20)} was also studied and it was again proved that this homolog had higher affinity to the membranous structure in the liver cell especially to the mitochondrial inner membrane. This high affinity of these homologs to the mitochondria especially to the inner membrane suggests the participation of them in some regulatory process in the mitochondrial function other than blood coagulation protein synthesis.