Changelian P S, Fearon D T
J Exp Med. 1986 Jan 1;163(1):101-15. doi: 10.1084/jem.163.1.101.
CR1 of neutrophils and monocytes may exist in a resting state, in which it only binds ligand-coated particles, or an activated state, in which it mediates phagocytosis. Because the activated state of CR1 can be induced by the stimulation of protein kinase C with PMA, CR1 was assessed for phosphorylation. Purified human neutrophils, monocytes, eosinophils, tonsilar lymphocytes, SB cells, and erythrocytes were labeled with 32PO4 and incubated with buffer or 100 ng/ml PMA. Membrane proteins were immunoprecipitated and analyzed by SDS-PAGE and autoradiography. CR1, unlike HLA class I heavy chain, was not constitutively phosphorylated by any cell type. PMA induced phosphorylation of CR1 in three phagocytic cell types, but did not induce the phosphorylation of CR3 or FcR. FMLP also induced the phosphorylation of CR1 in neutrophils. In contrast, PMA did not induce phosphorylation of CR1 in tonsilar B lymphocytes, SB cells, or erythrocytes, indicating restriction of this reaction to phagocytic cell types. This may be due to differences in the structure or presentation of the cytoplasmic domain of CR1 in phagocytic vs. nonphagocytic cells. Phosphorylation of CR2, however, did occur in PMA-treated B lymphocytes and SB cells, suggesting that this receptor, rather than CR1, may be involved in regulation of B lymphocyte function.
中性粒细胞和单核细胞的补体受体1（CR1）可能以静息状态存在，此时它仅结合包被配体的颗粒，也可能以激活状态存在，此时它介导吞噬作用。由于CR1的激活状态可由佛波酯（PMA）刺激蛋白激酶C诱导，因此对CR1的磷酸化情况进行了评估。将纯化的人中性粒细胞、单核细胞、嗜酸性粒细胞、扁桃体淋巴细胞、SB细胞和红细胞用32PO4标记，并与缓冲液或100 ng/ml PMA一起孵育。对膜蛋白进行免疫沉淀，并用SDS-聚丙烯酰胺凝胶电泳（SDS-PAGE）和放射自显影分析。与I类人白细胞抗原重链不同，CR1在任何细胞类型中都不是组成性磷酸化的。PMA诱导三种吞噬细胞类型中CR1的磷酸化，但不诱导CR3或FcR的磷酸化。N-甲酰甲硫氨酰-亮氨酰-苯丙氨酸（FMLP）也诱导中性粒细胞中CR1的磷酸化。相反，PMA不诱导扁桃体B淋巴细胞、SB细胞或红细胞中CR1的磷酸化，表明该反应仅限于吞噬细胞类型。这可能是由于吞噬细胞与非吞噬细胞中CR1细胞质结构域的结构或呈现方式存在差异。然而，CR2的磷酸化确实发生在经PMA处理的B淋巴细胞和SB细胞中，这表明该受体而非CR1可能参与B淋巴细胞功能的调节。
