Sidransky H, Verney E
Department of Pathology, George Washington University Medical Center, Washington, District of Columbia 20037, USA.
Amino Acids. 2000;18(2):103-16. doi: 10.1007/s007260050009.
This study evaluated whether cycloheximide, an inhibitor of protein synthesis, would affect the binding of L-tryptophan to rat hepatic nuclei or nuclear envelopes. Previous reports have indicated that the binding of L-tryptophan to hepatic nuclear envelope protein was saturable, stereospecific, and of high affinity. Also, the administration of L-tryptophan rapidly stimulated hepatic protein synthesis. In this study, we determined that the addition of cycloheximide in vitro inhibited 3H-tryptophan binding to hepatic nuclei or nuclear envelopes. Heat-treated cycloheximide failed to have this inhibitory binding effect. In vivo treatment of rats with cycloheximide diminished in vitro 3H-tryptophan binding to hepatic nuclei of treated rats compared to controls. Puromycin, another inhibitor of hepatic protein synthesis, when added in vitro did not affect 3H-tryptophan binding to hepatic nuclei but did diminish in vitro binding after in vivo treatment. Thus, cycloheximide added in vitro diminished 3H-tryptophan binding to hepatic nuclei probably by its structural effect on the receptor while cycloheximide administered in vivo may also act in part by inhibiting protein synthesis.
本研究评估了蛋白质合成抑制剂放线菌酮是否会影响L-色氨酸与大鼠肝细胞核或核膜的结合。先前的报告表明，L-色氨酸与肝核膜蛋白的结合具有饱和性、立体特异性和高亲和力。此外，给予L-色氨酸可迅速刺激肝脏蛋白质合成。在本研究中，我们确定在体外添加放线菌酮会抑制3H-色氨酸与肝细胞核或核膜的结合。经热处理的放线菌酮没有这种抑制结合的作用。与对照组相比，用放线菌酮对大鼠进行体内处理后，体外3H-色氨酸与处理过的大鼠肝细胞核的结合减少。嘌呤霉素是另一种肝脏蛋白质合成抑制剂，体外添加时不影响3H-色氨酸与肝细胞核的结合，但在体内处理后会减少体外结合。因此，体外添加的放线菌酮可能通过其对受体的结构作用减少3H-色氨酸与肝细胞核的结合，而体内给予的放线菌酮也可能部分通过抑制蛋白质合成起作用。
