Karinch A M, deMello D E, Floros J
Department of Cellular and Molecular Physiology, Pennsylvania State University, College of Medicine, Hershey 17033, USA.
Biochem J. 1997 Jan 1;321 ( Pt 1)(Pt 1):39-47. doi: 10.1042/bj3210039.
Human pulmonary surfactant protein A (SP-A) is encoded by two genes, SP-A1 and SP-A2, that exhibit coding sequence (allelic) and 5' splicing variability. In this report we determine the effect of the genetic variability within the SP-A1 and SP-A2 genes on the level of SP-A mRNAs and on the SP-A2 splicing variants in different individuals. We analysed mRNA specimens from 23 unrelated adults using genotype analysis, Northern analysis and primer extension, and made the following observations. (1) The level of SP-A mRNA varies among individuals (coefficient of variation = 0.49). One SP-A genotype (6A(2)6A(2)1A(0)1A0) appears to be associated with a low to moderate level of SP-A mRNA. (2) The SP-A1/SP-A2 mRNA ratio varies among individuals, from 0.94 (lowest) to 6.80 (highest) within the study population. One genotype appears to be associated with a moderate to high SP-A1/SP-A2 mRNA ratio and another with a low to moderate ratio. (3) There is no correlation between the level of SP-A mRNA and the SP-A1/SP-A2 mRNA ratio. (4) Variability in the ratio of the major SP-A2 splice variants among individuals results from nucleotide differences in the splice-recognition sequence of specific SP-A2 alleles. The SP-A mRNA levels, the SP-A1/SP-A2 mRNA ratio, and the ratio of the major SP-A2 splice variants have a genetic basis in that they vary depending upon the specific SP-A alleles present.
人肺表面活性物质蛋白A（SP-A）由两个基因SP-A1和SP-A2编码，这两个基因表现出编码序列（等位基因）和5'剪接变异性。在本报告中，我们确定了SP-A1和SP-A2基因内的遗传变异性对不同个体中SP-A mRNA水平和SP-A2剪接变体的影响。我们使用基因型分析、Northern分析和引物延伸分析了23名无关成年人的mRNA样本，并得出以下观察结果。（1）个体间SP-A mRNA水平存在差异（变异系数=0.49）。一种SP-A基因型（6A(2)6A(2)1A(0)1A0）似乎与低至中等水平的SP-A mRNA相关。（2）个体间SP-A1/SP-A2 mRNA比率不同，在研究人群中从0.94（最低）到6.80（最高）。一种基因型似乎与中等至高的SP-A1/SP-A2 mRNA比率相关，另一种与低至中等比率相关。（3）SP-A mRNA水平与SP-A1/SP-A2 mRNA比率之间无相关性。（4）个体间主要SP-A2剪接变体比率的差异是由特定SP-A2等位基因的剪接识别序列中的核苷酸差异引起的。SP-A mRNA水平、SP-A1/SP-A2 mRNA比率以及主要SP-A2剪接变体的比率具有遗传基础，因为它们会根据存在的特定SP-A等位基因而有所不同。
