Journal Article

Formation of Retinoylated Proteins from Retinoyl-CoA in Rat Tissues

Yoshinori Kubo, Masashi Wada, Toshihiro Ohba and Noriko Takahashi

in The Journal of Biochemistry

Published on behalf of The Japanese Biochemical Society

Volume 138, issue 4, pages 493-500
Published in print October 2005 | ISSN: 0021-924X
Published online October 2005 | e-ISSN: 1756-2651 | DOI: http://dx.doi.org/10.1093/jb/mvi145
Formation of Retinoylated Proteins from Retinoyl-CoA in Rat Tissues

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Retinoylation (acylation of proteins by retinoic acid) is considered as one mechanism of retinoic acid (RA) action occurring in cells in vitro and in vivo. Previously, our studies showed that in rat tissues the formation of retinoyl-CoA from RA, the first step of retinoylation, required ATP, CoA and MgCl2. In the current study, we examined whether the transfer of retinoyl-CoA into proteins, the second step of retinoylation, occurs in rat tissues. [3H]-Labeled-retinoyl-CoA bound covalently to proteins in rat liver, kidney, testis, and brain. The levels of incorporation of retinoyl-CoA into proteins were higher in vitamin A–deficient rats than in normal ones. The formation of retinoylated proteins depended on the incubation time, and the concentrations of retinoyl-CoA and homogenate. The reaction was suppressed by fatty acyl-CoAs and palmitic acid, but not by arachidonic acid. The Vmax and Km values for retinoyl-CoA in the formation of retinoylated proteins using a crude liver extract were estimated to be 2,597.3 pmol/min/mg protein and 9.5 × 10−5 M, respectively. Retinoylated proteins formed from retinoyl-CoA, including a 17 kDa protein exhibiting high radioactivity, disappeared in the presence of 2-mercaptoethanol, indicating that RA was linked to the proteins through a thioester bond. These results demonstrate that retinoylation in rat tissues occurs via retinoyl-CoA formed from RA. This process may play a significant physiological role in cells.

Keywords: retinoic acid; retinoyl-CoA; retinoylation; rat tissue; transfer; RA, retinoic acid; PBS, phosphate-buffered saline (1.5 mM KH2PO4, 8.1 mM Na2HPO4, 136.9 mM NaCl, pH 7.2); EDTA, ethylenediaminetetraacetic acid; BSA, bovine serum albumin; DTT, dithiothreitol; ATP, adenosine triphosphate; CoA, coenzyme A; RAR, retinoic acid nuclear receptor

Journal Article.  5155 words.  Illustrated.

Subjects: Biochemistry

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