Korsgren C, Cohen C M
Department of Biomedical Research, St. Elizabeth's Hospital, Boston, MA 02135.
Proc Natl Acad Sci U S A. 1991 Jun 1;88(11):4840-4. doi: 10.1073/pnas.88.11.4840.
Human erythrocyte band 4.2 is a major membrane-associated protein with an important, but still undefined, role in erythrocyte survival. We previously sequenced the complete cDNA for band 4.2 and showed that the protein has a strong sequence identity with the transglutaminase family of proteins but lacks transglutaminase activity. Here we have analyzed the genomic organization of band 4.2. The band 4.2 gene is approximately 20 kilobases, consisting of 13 exons and 12 introns. Reticulocytes contain two different sized messages for band 4.2, and our results show that the major, smaller, message is produced by alternative splicing within band 4.2 exon I. The upstream region of the gene has several prospective promoter elements arranged in a pattern similar to that of two other erythroid genes, beta-globin and porphobilinogen deaminase. Alignment of the band 4.2 amino acid sequence with that of the a subunit of human coagulation factor XIII and division of the sequences into exons reveal a remarkable correspondence, and in most cases identity, in the sizes of the paired exons. Moreover, each corresponding intron of the two genes is of an identical splice junction class. These and other similarities suggest that the gene for band 4.2 is closely related to and possibly derived from that for the a subunit of factor XIII and that the proteins may share common structural and functional properties.
人红细胞带4.2是一种主要的膜相关蛋白，在红细胞存活中发挥着重要但仍不明确的作用。我们之前对带4.2的完整cDNA进行了测序，结果表明该蛋白与转谷氨酰胺酶家族蛋白具有很强的序列同源性，但缺乏转谷氨酰胺酶活性。在此，我们分析了带4.2的基因组结构。带4.2基因约为20千碱基，由13个外显子和12个内含子组成。网织红细胞含有两种不同大小的带4.2信使RNA，我们的结果表明，主要的较小的信使RNA是由带4.2外显子I内的可变剪接产生的。该基因的上游区域有几个潜在的启动子元件，其排列模式与另外两个红系基因β-珠蛋白和胆色素原脱氨酶相似。将带4.2的氨基酸序列与人凝血因子XIII a亚基的氨基酸序列进行比对，并将序列划分为外显子，结果显示配对外显子的大小存在显著对应关系，在大多数情况下是相同的。此外，这两个基因的每个相应内含子都属于相同的剪接连接类型。这些以及其他相似之处表明，带4.2基因与因子XIII a亚基的基因密切相关，可能源自该基因，并且这两种蛋白可能具有共同的结构和功能特性。
