title: Induction of increased calcium uptake in liposomes having membrane proteins of chicken erythrocytes by S-adenosylmethionine.
abstract: Liposomes having membrane proteins of chicken erythrocytes were prepared and the effect of S-adenosylmethionine on 45Ca2+ uptake into the liposomes was investigated. S-Adenosylmethionine, a donor of methyl groups in enzymatic methylation, induced an increase of 45Ca2+ uptake into the proteoliposomes with membrane proteins but not into the liposomes without membrane proteins. Increased release of 45Ca2+ from the inside of the proteoliposomes was also induced by S-adenosylmethionine. These increases of uptake and release of 45Ca2+ were inhibited by S-adenosylhomocystein, an inhibitor of enzymatic methylation. Furthermore, membrane proteins from chicken erythrocytes showed protein and phospholipid methyltransferase activities. The uptake of other materials, 3-0-[methyl-3H]glucose, alpha-[1-14C]aminoisobutyric acid, 42K+ and 54Mn2+, into the proteoliposomes was not increased by S-adenosylmethionine. These results suggest that enzymatic methylation of membrane components may have an important role in the regulation of calcium transport in the chicken erythrocyte membrane and this regulation is rather specific for calcium.
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability; D002645:Chickens; D004910:Erythrocyte Membrane / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D008081:Liposomes; D008565:Membrane Proteins / Q000097:blood; D008745:Methylation; D010743:Phospholipids / Q000378:metabolism; D012436:S-Adenosylmethionine / Q000494:pharmacology*
chemical_list: D008081:Liposomes; D008565:Membrane Proteins; D010743:Phospholipids; D012436:S-Adenosylmethionine; D002118:Calcium