Osteosarcoma cytosol factor promotes parathyroid hormone stimulation of adenylate cyclase independent of GTP.
Osteosarcoma cytosol factor promotes parathyroid hormone stimulation of adenylate cyclase independent of GTP.
复制标题
骨肉瘤胞质因子促进甲状旁腺激素刺激腺苷酸环化酶，不依赖于 GTP。
DOI：
10.1016/0304-4165(80)90325-6
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发表时间：
1980
期刊：
影响因子：
--
通讯作者：
Rodan,GA
中科院分区：
文献类型：
--
作者：
Egan,JJ;Majeska,RJ;Rodan,GA
从大鼠骨肉瘤细胞液中提取的腺苷酸环化酶（ATP焦磷酸裂解酶（环化），EC 4.6.1.1）刺激因子经离子交换层析纯化600倍。该因子的表观Mr为20 000，不耐寒，但在-20 °C的10%甘油中仍保持活性。该因子增强了甲状旁腺激素对腺苷酸环化酶的刺激，并恢复了激素对用0.5 M NaCl洗涤的膜的反应性。100 μM GDP-β-S完全消除了GTP对基础腺苷酸环化酶和腺苷酸环化酶的增强作用，但不抑制这种“GTP样”效应。该因子还线性化（在双倒数图）的向下凹的Mg 2+依赖的腺苷酸环化酶，增加了Mg 2+的酶的表观亲和力。该因子在两个克隆骨肉瘤细胞系中的存在与甲状旁腺素刺激的腺苷酸环化酶。因子刺激是不存在的，而GTP刺激保留在无反应克隆。通过体内传代恢复因子和激素敏感性。因此，该因子可能代表了细胞调节激素反应的鸟苷酸非依赖性途径。
The adenylate cyclase (ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1)-stimulating factor from rat osteosarcoma cytosol was purified 600-fold by ion-exchange chromatography. The factor has an apparentMrof 20 000, is cold-labile, but retains activity at −20°C in 10% glycerol.The factor enhanced parathyroid hormone stimulation of adenylate cyclase and restored hormone responsiveness to membranes washed with 0.5 M NaCl. These ‘GTP-like’ effects were not inhibited by 100 μM GDP-β-S, which completely abolished the GTP enhancement of both basal and hormone-stimulated adenylate cyclase.Adenylate cyclase activity in the presence of the stimulating factor was linear with time, and showed hyperbolic dependence on factor concentration. The factor also linearized (in double reciprocal plots) the downward-concave Mg2+-dependence of adenylate cyclase, increasing the apparent affinity of the enzyme for Mg2+.The presence of the factor in two clonal osteosarcoma cell lines correlated with parathyroid hormone-stimulatable adenylate cyclase. Factor stimulation was absent while GTP stimulation was retained in the hormone-nonresponsive clone. Factor and hormone sensitivity were restored by in vivo passage. This factor thus may represent a guanyl nucleotide-independent path for cellular regulation of hormone response.