Eggermont J A, Wuytack F, Verbist J, Casteels R
Laboratorium voor Fysiologie, K.U. Leuven, Belgium.
Biochem J. 1990 Nov 1;271(3):649-53. doi: 10.1042/bj2710649.
The expression of the gene 2 sarcoplasmic/endoplasmic-reticulum Ca2(+)-pump isoforms (SERCA2a and SERCA2b) and of phospholamban was studied in pig smooth muscle of the stomach, longitudinal ileum, pulmonary artery and aorta. mRNA levels were determined using an RNAase protection assay. The SERCA2 isoforms and phospholamban were tested on Western blots with a panel of antibodies, some of which were isoform-specific. The pig smooth-muscle tissues all contained comparable SERCA2 mRNA levels, but these levels were 10-20-fold lower than SERCA2 mRNA levels in cardiac muscle. Of the SERCA2 mRNAs in smooth muscle, 72-81% encoded the non-muscle isoform (SERCA2b), and Western blot analysis with isoform-specific antibodies confirmed that the SERCA2b isoform is the predominant endoplasmic-reticulum Ca2(+)-pump in smooth muscle. In contrast with SERCA2 mRNA levels, phospholamban mRNA levels varied by 12-fold between the different pig smooth-muscle tissues, with low and very low levels in the pig pulmonary artery and the pig aorta respectively. The differential expression of phospholamban was also confirmed on Western blots. The finding that the phospholamban content varied between the different smooth-muscle tissues whereas the SERCA2 expression remained rather constant indicates that, in pig smooth muscle, the expression of phospholamban is not coupled with that of SERCA2.
研究了胃、回肠纵肌、肺动脉和主动脉的猪平滑肌中基因2的肌浆网/内质网Ca2+泵亚型（SERCA2a和SERCA2b）及受磷蛋白的表达。使用核糖核酸酶保护分析法测定mRNA水平。用一组抗体在蛋白质免疫印迹法上检测SERCA2亚型和受磷蛋白，其中一些抗体是亚型特异性的。猪平滑肌组织中SERCA2 mRNA水平均相当，但这些水平比心肌中的SERCA2 mRNA水平低10 - 20倍。在平滑肌的SERCA2 mRNA中，72 - 81%编码非肌肉亚型（SERCA2b），用亚型特异性抗体进行的蛋白质免疫印迹分析证实，SERCA2b亚型是平滑肌中主要的内质网Ca2+泵。与SERCA2 mRNA水平相反，不同猪平滑肌组织中受磷蛋白mRNA水平相差12倍，在猪肺动脉和猪主动脉中分别处于低水平和极低水平。蛋白质免疫印迹法也证实了受磷蛋白的差异表达。受磷蛋白含量在不同平滑肌组织中有所不同而SERCA2表达保持相对恒定这一发现表明，在猪平滑肌中，受磷蛋白的表达与SERCA2的表达没有关联。
