Hamid J, Burness A T
Faculty of Medicine, Memorial University of Newfoundland, St John's, Canada.
Nucleic Acids Res. 1990 Oct 11;18(19):5829-36. doi: 10.1093/nar/18.19.5829.
The major sialoglycoprotein in the human red cell surface membrane, glycophorin A is encoded by a single gene. However, this gene gives rise to three species of glycophorin A mRNA of sizes about 1.0, 1.7 and 2.8 kilobases in reticulocytes, foetal liver cells and erythroleukaemic K562 cells. In an investigation of how the three mRNAs originated, we showed by primer extension analysis that all three mRNAs in K562 cells had identical 5' termini and, by nucleotide sequencing of correlated cDNAs, that they had identical coding regions, except for the well-known glycophorin AM-AN polymorphism. However, we found also by sequencing the cDNAs that the mRNAs apparently differed from each other in the lengths of their 3' untranslated regions. This was confirmed by Northern blot analysis which also provided evidence that the three mRNAs originated by use of different polyadenylation signals of which seven were found in the longest cDNA we analyzed.
人红细胞表面膜中的主要唾液糖蛋白血型糖蛋白A由单个基因编码。然而，该基因在网织红细胞、胎儿肝细胞和红白血病K562细胞中产生三种大小约为1.0、1.7和2.8千碱基的血型糖蛋白A mRNA。在一项关于这三种mRNA如何产生的研究中，我们通过引物延伸分析表明，K562细胞中的所有三种mRNA具有相同的5'末端，并且通过对相关cDNA的核苷酸测序表明，除了众所周知的血型糖蛋白A M-AN多态性外，它们具有相同的编码区。然而，我们通过对cDNA测序还发现，这些mRNA在其3'非翻译区的长度上明显彼此不同。Northern印迹分析证实了这一点，该分析还提供了证据，表明这三种mRNA是通过使用不同的聚腺苷酸化信号产生的，在我们分析的最长cDNA中发现了其中七个信号。
