α1A-肾上腺素受体与骨形成蛋白-1片段在人胚肾293细胞中的结合

用酵母双杂交方法发现骨形成蛋白-1(bone morphogenetic protein-1,BMP-1)的片段可以与α1A-肾上腺素受体(adrenergic receptor,AR)的细胞内游离C末端结合。进一步探讨了二者在哺乳动物表达系统人胚肾293细胞(human embryonic cell 293,HEK293)中的相互作用。采用PCR方法构建含BMP-1片段eDNA的真核表达质粒PCP3HA,将其与含全长人α1A-AR eDNA的质粒PDT-α1A分别或共同转染HEK293细胞,用免疫印迹法检测到α1A-AR和BMP-1在HEK293细胞有相应的蛋白表达。用酶联免疫吸附实验对免疫印迹鉴定过的细胞裂解液进行检测,观察到空白对照组,单独转染PDTα1A-和单独转染PCP3HA的细胞,OD490值分别为0.034±0.027、0.042±0.019、0.030±0.0096,三者之间无显著性差异。共转染PDT-α1A和PCP3HA的细胞,OD490值为0.57±0.12,较其它三组具有显著性差异(均P<0.001)。免疫共沉淀结果显示,单独转染PDT-α1A或PCP3HA的细胞,免疫沉淀产物中均不能检测到BMP-1片段,只有共转染PDT-α1A和PCP3HA的细胞,在其免疫沉淀产物中能检测到BMP-1片段。ELISA和免疫沉淀结果均表明α1A-AR与BMP-1的片段在HEK293细胞中存在蛋白水平的相互作用。

Binding between alpha 1A-adrenergic receptor and segment of bone morphogenetic protein-1 in human embryonic cell 293

Using matchmaker yeast two-hybrid system, it has been demonstrated that there exists an interaction between the cellular C terminal of alpha(1A)-adrenergic receptor (alpha(1A)-AR) and a segment of bone morphogenetic protein-1 (BMP-1). In the present study binding between the two proteins was further determined in human embryonic cell 293 (HEK293), a mammalian expression system. Mammalian expression vector PCP3HA was constructed by PCR and consisted of segments of BMP-1 cDNA, and vector PDT-alpha(1A) consisted of the full-length cDNA of human alpha(1A)-AR. They were transfected to HEK293 cells and examined by Western blot. alpha(1A)-AR and the segment of BMP-1 could be detected in the lysis of transfected cells. Then binding between alpha(1A)-AR and the segment of BMP-1 in HEK293 cell was determined by enzyme-linked immunosorbent assays (ELISA) and co-immunoprecipitation. In ELISA experiment, the ELISA microwell plate was first coated with anti-FLAG M2 antibody, which recognizes the FLAG-tagged alpha(1A)-AR, then the cell lysis, anti-HA rabbit polyclonal antibody and HRP conjugated anti-rabbit antibody were added in turn. The OD(490) values among the control group, PDT-alpha(1A) transfection group and PCP3HA transfection group, exhibited no significant difference (0.034+/-0.027, 0.042+/-0.019, 0.030+/-0.0096), but the OD(490) values of PDT-alpha(1A) and PCP3HA co-transfection group (0.57+/-0.12) were significantly higher than those of the other groups (P<0.001, respectively). In co-immunoprecipitation experiments, HEK293 cells expressing alpha(1A)-AR or/and segment of BMP-1 were lysed and incubated with anti-FLAG M2 antibody, then the immunoprecipitation pellet was immunoblotted with either the HRP conjugated anti-FLAG antibody or the anti-HA antibody, which recognizes the HA-tagged segment of BMP-1. Segment of BMP-1 was present in the pellet immunoprecipitation of PDT-alpha(1A) and PCP3HA co-transfected group. In conclusion, the results indicate that alpha(1A)-AR and the segment of BMP-1 are present in the same complex in HEK293 cells.