Abstract: The peptide-sepcific antipobies of the Ca²⁺/H⁺ antiporter clearly reacted with a 44.5 kD protein from rice root plasma membrane by immunoblotting. Ca²⁺ transport activities of rice root plasma membrane by the filtration method using ⁴⁵Ca²⁺, indicated that there was a Ca²⁺/H⁺ antiporter(OsCAX2) depended on transmembrane proton gradient in the rice root plasma membrane, and manganese ion could restrain Ca²⁺ transport activities of OsCAX2 partially. Kinetics analysis showed that the V_max of OsCAX2 was 34.72 nmol/(min·mg), the K_m was 3.83 μmol/L and the optimum pH value was 7.2.

Key words: Ca2+/H+ antiporter, rice, root, plasma membrane

摘要： 由Ca2+/H+反向转运体蛋白的特异多肽制备的抗体，通过免疫印迹显示水稻根质膜上存在分子量为44.5 kD的蛋白。同位素闪烁记数法检测水稻根质膜上45Ca2+转运活性显示存在依赖于跨膜质子梯度的Ca2+/H+反向转运体，Mn2+可部分地抑制其转运活性。动力学分析表明，OsCAX2的Vmax=34.72 nmol/（min·mg）， Km=3.83 μmol/L，其最适pH为7.2。

关键词: Ca2+/H+反向转运体, 水稻, 根, 质膜