Choi H S, Wojchowski D M, Sytkowski A J
J Biol Chem. 1987 Mar 5;262(7):2933-6.
The phosphorylation of a prominent 43-kDa phosphoprotein (pp43) in the membranes of normal murine erythroid cells was reduced markedly by exposure of the membranes to highly purified erythropoietin. A virtually identical reduction of pp43 phosphorylation was seen when erythropoietin-responsive Rauscher murine erythroleukemia cell membranes were exposed to the hormone. This effect was both time-dependent, occurring within 30 min after erythropoietin exposure, and concentration-dependent. Phosphoamino acid analysis revealed that pp43 is phosphorylated on serine residues. The results provide the first evidence that rapid alterations in membrane protein phosphorylation may serve as a trans-membrane signal for erythropoietin.
正常小鼠红细胞细胞膜中一种显著的43-kDa磷蛋白（pp43）的磷酸化，在细胞膜暴露于高度纯化的促红细胞生成素后显著降低。当促红细胞生成素反应性劳舍尔小鼠红白血病细胞膜暴露于该激素时，pp43磷酸化也出现几乎相同程度的降低。这种效应具有时间依赖性，在促红细胞生成素暴露后30分钟内发生，并且具有浓度依赖性。磷酸氨基酸分析表明，pp43在丝氨酸残基上被磷酸化。这些结果首次证明，膜蛋白磷酸化的快速改变可能作为促红细胞生成素的跨膜信号。
