The property and function of tubulin-like protein which is integrated in membrane systems of higher plants

用3-吲哚乙酸（IAA）和赤霉素A_3 （GA_3）孵育红豆片段，发现一种推测整合在膜组分中的a-微管蛋白同工异构体在4h后消失。6-二甲氨基嘌呤（6-DMAP）不仅可以阻止ab的消失，同时也可以阻止ga_3诱导的伸长促进。纯化后的质膜中含有微管蛋白，经激素处理后微管蛋白不消失，在二维PAGE上表现出独特的行为。免疫电镜观察显示，微管蛋白具有典型的环状结构。环状结构的直径约为30 nm，与末端配合物相似。事实上，含有环状结构的多糖在Ca^<2+>存在下与udp -葡萄糖孵育后，会形成丰富的丝状结构。虽然大部分纤维是b-1,3-葡聚糖，但经b-1,3-葡聚糖酶处理后留下的少量硬纤维推测为纤维素。在液泡膜中发现了激素处理后消失的小管蛋白。根据二价阳离子的存在，推测液泡膜中的微管蛋白与28kda蛋白有关。

When the segments of azuki bean were incubated with 3-indoleacetic acid (IAA) plus gibberellin A_3 (GA_3), one isoform of a-tubulin, which was speculated to be integrated in membraneous fraction, was found to disappear after 4h.6-Dimethylaminopurine (6-DMAP) prevented not only the disappearance of the ab but also simulataneously prevented the GA_3-induced promotion of elongation.However, purified plasma membrane contained tubulin which did not disappeare after treatment with hormones ans showed unique behavior on 2-D PAGE.Such tubulin was revealed to be integrated in characteristic ring-shaped structures by immunoelectron microscopic observation. The size of the ring-shaped structures was about 30 nm in diameter and resembled to that of terminal complexes.In fact, the formation of abundant filamentous structures of polysaccharide occurred in the preparations which contained ring-shaped structures by the incubation with UDP-glucose in the presence of Ca^<2+>. Although most filaments were b-1,3-glucan, the minor stiff filaments which remained after treatment with b-1,3-glucanase were speculated to be cellulose. Tubulin which disappeare after the treatment with hormone was found in vacuolar membrane. Tubulin in vacuolar membrane was speculated to be associated with 28 KDa protein depending on the presence of divalent cation.