Bloodgood R A, Salomonsky N L
Department of Cell Biology, University of Virginia School of Medicine, Charlottesville 22908.
J Cell Biol. 1994 Nov;127(3):803-11. doi: 10.1083/jcb.127.3.803.
Cross-linking of Chlamydomonas reinhardtii flagellar membrane glycoproteins results in the directed movements of these glycoproteins within the plane of the flagellar membrane. Three carbohydrate-binding reagents (FMG-1 monoclonal antibody, FMG-3 monoclonal antibody, concanvalin A) that induce flagellar membrane glycoprotein crosslinking and redistribution also induce the specific dephosphorylation of a 60-kD (pI 4.8-5.0) flagellar phosphoprotein (pp60) that is phosphorylated in vivo on serine. Ethanol treatment of live cells induces a similar specific dephosphorylation of pp60. Affinity adsorption of flagellar 32P-labeled membrane-matrix extracts with the FMG-1 monoclonal antibody and concanavalin A demonstrates that pp60 binds to the 350-kD class of flagellar membrane glycoproteins recognized by the FMG-1 monoclonal antibody. In vitro, protein phosphatase 2B (calcineurin) removes 60% of the 32P from pp60; this correlates well with previous observations that directed flagellar glycoprotein movements are dependent on micromolar calcium in the medium and are inhibited by calcium channel blockers and calmodulin antagonists. The data reported here are consistent with the dephosphorylation of pp60 being a step in the signaling pathway that couples flagellar membrane glycoprotein cross-linking to the directed movements of flagellar membrane glycoproteins.
莱茵衣藻鞭毛膜糖蛋白的交联导致这些糖蛋白在鞭毛膜平面内的定向运动。三种诱导鞭毛膜糖蛋白交联和重新分布的碳水化合物结合试剂（FMG-1单克隆抗体、FMG-3单克隆抗体、伴刀豆球蛋白A）也诱导一种60-kD（pI 4.8 - 5.0）鞭毛磷蛋白（pp60）的特异性去磷酸化，该磷蛋白在体内丝氨酸上被磷酸化。用乙醇处理活细胞会诱导pp60发生类似的特异性去磷酸化。用FMG-1单克隆抗体和伴刀豆球蛋白A对鞭毛32P标记的膜-基质提取物进行亲和吸附表明，pp60与FMG-1单克隆抗体识别的350-kD类鞭毛膜糖蛋白结合。在体外，蛋白磷酸酶2B（钙调神经磷酸酶）从pp60上去除60%的32P；这与之前的观察结果很好地相关，即鞭毛糖蛋白的定向运动依赖于培养基中的微摩尔钙，并受到钙通道阻滞剂和钙调蛋白拮抗剂的抑制。此处报道的数据与pp60的去磷酸化是将鞭毛膜糖蛋白交联与鞭毛膜糖蛋白定向运动相偶联的信号通路中的一个步骤一致。
