Cione Erika, Tucci Paola, Chimento Adele, Pezzi Vincenzo, Genchi Giuseppe
Dipartimento Farmaco-Biologico, Edificio Polifunzionale, Università della Calabria, 87036 Rende (Cosenza), Italy.
J Bioenerg Biomembr. 2005 Feb;37(1):43-8. doi: 10.1007/s10863-005-4122-1.
The covalent incorporation of [(3)H]all-trans-retinoic acid into proteins has been studied in Leydig (TM-3) cells. The maximum retinoylation activity of Leydig cells proteins was 570+/- 27 fmoles/8 x 10(4) cells at 37( composite function)C. About 95% of [(3)H]retinoic acid was trichloroacetic acid-soluble after proteinase-K digestion or after hydrolysis with hydroxylamine. Thus, retinoic acid is most probably linked to proteins as a thiol ester. The retinoylation process was inhibited by 13-cis-retinoic acid and 9-cis-retinoic acid with IC(50) values of 0.6 and 1.2 microM respectively. Dibutyryl-cAMP and forskolin increased the retinoylation activity by 75 and 81% at 500 and 25 microM respectively. Also hCG increased the retinoylation binding activity of 110% at 250 ng/mL. After cycloheximide treatment of the Leydig cells the binding activity of [(3)H]RA was about the same that in the control, suggesting that the bond occurs on proteins in pre-existing cells. Retinoylation was not inhibited by high concentrations of palmitic or myristic acids (500 microM); on the contrary, there was an increase of the binding activity of about 60 and 50% respectively.
已在睾丸间质（TM-3）细胞中研究了[(3)H]全反式视黄酸与蛋白质的共价结合。在37℃时，睾丸间质细胞蛋白质的最大视黄酰化活性为570±27飞摩尔/8×10(4)个细胞。蛋白酶-K消化或用羟胺水解后，约95%的[(3)H]视黄酸可溶于三氯乙酸。因此，视黄酸很可能以硫酯的形式与蛋白质相连。13-顺式视黄酸和9-顺式视黄酸抑制视黄酰化过程，IC(50)值分别为0.6和1.2微摩尔。二丁酰环磷腺苷和福斯高林分别在500和25微摩尔时使视黄酰化活性提高75%和81%。同样，人绒毛膜促性腺激素（hCG）在250纳克/毫升时使视黄酰化结合活性提高110%。用环己酰亚胺处理睾丸间质细胞后，[(3)H]视黄酸的结合活性与对照大致相同，这表明该键发生在已存在细胞中的蛋白质上。高浓度的棕榈酸或肉豆蔻酸（500微摩尔）不会抑制视黄酰化；相反，结合活性分别增加了约60%和50%。
