Retinoylation reaction of proteins in Leydig (TM-3) cells.
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.
Cione
Erika
E
Dipartimento Farmaco-Biologico, Edificio Polifunzionale, Università della Calabria, 87036 Rende (Cosenza), Italy.
Tucci
Paola
P
Chimento
Adele
A
Pezzi
Vincenzo
V
Genchi
Giuseppe
G
D000818:Animals; D002460:Cell Line; D007700:Kinetics; D007985:Leydig Cells / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D011865:Radioisotope Dilution Technique; D014212:Tretinoin / Q000378:metabolism*; D014316:Tritium
D011506:Proteins; D014316:Tritium; D014212:Tretinoin