Characterization of the hypertonically induced tyrosine phosphorylation of erythrocyte band 3.
Characterization of the hypertonically induced tyrosine phosphorylation of erythrocyte band 3.
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DOI：
10.1042/bj3350305
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发表时间：
1998-10
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影响因子：
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通讯作者：
G. Minetti;C. Seppi;A. Ciana;Cesare Balduini;Philip S. Low;A. Brovelli
中科院分区：
文献类型：
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作者：
G. Minetti;C. Seppi;A. Ciana;Cesare Balduini;Philip S. Low;A. Brovelli
人红细胞带3迅速磷酸化酪氨酸残基后暴露于高压条件下的红细胞。这种磷酸化反应的驱动力似乎是细胞体积的减少，因为(1)3带磷酸酪氨酸含量的变化准确地跟踪红细胞体积的反复变化，通过几个周期的肿胀和收缩；(2)带3磷酸化水平与所使用的渗透液无关，但对细胞收缩的大小非常敏感；(3)红细胞在细胞内渗透压增加但体积不变的条件下暴露于高渗缓冲液中（制氨抑素处理的细胞）不会促进酪氨酸磷酸化的增加。我们假设收缩诱导的酪氨酸磷酸化是由细胞内拥挤增加引起的排除体积效应引起的，或者是由伴随细胞体积减少而发生的膜曲率变化引起的。虽然带3的净磷酸化状态被证明是由于组成活性酪氨酸磷酸酶和组成活性酪氨酸激酶之间的微妙平衡，但在细胞收缩期间磷酸化的增加被证明是由后者的激活特异性地产生的。此外，体积敏感的红细胞酪氨酸激酶的特殊抑制模式与p72syk相匹配，p72syk是一种在体内已知与能带3相关的酪氨酸激酶，这表明该激酶参与了体积依赖性反应。
Human erythrocyte band 3 becomes rapidly phosphorylated on tyrosine residues after exposure of erythrocytes to hypertonic conditions. The driving force for this phosphorylation reaction seems to be a decrease in cell volume, because (1) changes in band 3 phosphotyrosine content accurately track repeated changes in erythrocyte volume through several cycles of swelling and shrinking; (2) the level of band 3 phosphorylation is independent of the osmolyte employed but strongly sensitive to the magnitude of cell shrinkage; and (3) exposure of erythrocytes to hypertonic buffers under conditions in which intracellular osmolarity increases but volume does not change (nystatin-treated cells) does not promote an increase in tyrosine phosphorylation. We hypothesize that shrinkage-induced tyrosine phosphorylation results either from an excluded-volume effect, stemming from an increase in intracellular crowding, or from changes in membrane curvature that accompany the decrease in cell volume. Although the net phosphorylation state of band 3 is shown to be due to a delicate balance between a constitutively active tyrosine phosphatase and constitutively active tyrosine kinase, the increase in phosphorylation during cell shrinkage was demonstrated to derive specifically from an activation of the latter. Further, a peculiar inhibition pattern of the volume-sensitive erythrocyte tyrosine kinase that matched that of p72syk, a tyrosine kinase already known to associate with band 3 in vivo, suggested the involvement of this kinase in the volume-dependent response.