Metabolism of S-adenosylmethionine in rat hepatocytes: transfer of methyl group from S-adenosylmethionine by methyltransferase reactions

Journal Article · Mon Aug 19 04:00:00 EDT 1985 · Life Sci.; (United States)

DOI:https://doi.org/10.1016/0024-3205(85)90434-5· OSTI ID:5359181

Tsukada, K; Abe, T; Kuwahata, T; Mitsui, K

Treatment of rats with a methionine diet leads not only to a marked increase of S-adenosylmethionine synthetase in liver, but also to the increase of glycine, guanidoacetate and betaine-homocysteine methyltransferases. The activity of tRNA methyltransferase decreased with the increased amounts of methionine in the diets. However, the activities of phospholipids and S-adenosylmethionine-homocysteine methyltransferases did not show any significant change. When hepatocarcinogenesis induced by 2-fluorenylacetamide progresses, the activities of glycine and guanidoacetate methyltransferases in rat liver decreased, and could not be detected in tumorous areas 8 months after treatment. The levels of S-adenosylmethionine in the liver also decreased to levels of one-fifth of control animals at 8 months. The uptake and metabolism of (methyl-/sup 3/H)-methionine and -S-adenosylmethionine have been investigated by in vivo and isolated hepatocytes. The uptake of methionine and transfer of methyl group to phospholipid in the cells by methionine were remarkably higher than those by S-adenosylmethionine. These results indicate that phospholipids in hepatocytes accept methyl group from S-adenosylmethionine immediately, when it is synthesized from methionine, before mixing its pool in the cells. 39 references, 1 figure, 2 tables.

• Research Organization: Tokyo Medical and Dental Univ., Japan
• OSTI ID: 5359181
• Journal Information: Life Sci.; (United States), Journal Name: Life Sci.; (United States) Vol. 37:7; ISSN LIFSA
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ANIMALS
BODY
CARBOXYLIC ACIDS
DIGESTIVE SYSTEM
DRUGS
ENZYME ACTIVITY
ENZYMES
ESTERS
GLANDS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIGASES
LIPIDS
LIPOTROPIC FACTORS
LIVER
MAMMALS
METABOLISM
METHIONINE
METHYL TRANSFERASES
NUCLEIC ACIDS
ONCOGENIC TRANSFORMATIONS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANS
PHOSPHOLIPIDS
RATS
RNA
RODENTS
TRACER TECHNIQUES
TRANSFER RNA
TRANSFERASES
TRITIUM COMPOUNDS
VERTEBRATES