Streuli M, Hall L R, Saga Y, Schlossman S F, Saito H
Division of Tumor Immunology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115.
J Exp Med. 1987 Nov 1;166(5):1548-66. doi: 10.1084/jem.166.5.1548.
Leukocyte common antigens (LCAs, also known as T200 and CD 45) are integral membrane proteins expressed exclusively on hematopoietic cells. These molecules exhibit varying molecular masses and epitopes when expressed in different cell types. To determine the genetic bases for the generation of this diversity, three classes of human LCA cDNA clones that are different near their 5' ends have been isolated. These differences arose as a result of differential usage of three exons as determined from an analysis of a genomic DNA clone. Furthermore, Northern blot analysis with LCA exon-specific probes demonstrates the existence of at least two more LCA mRNA forms that are generated by differential splicing. A comparison of the human and mouse LCA protein sequences revealed a marked difference only in the extracellular domain.
白细胞共同抗原(LCAs,也称为T200和CD 45)是仅在造血细胞上表达的整合膜蛋白。这些分子在不同细胞类型中表达时表现出不同的分子量和表位。为了确定这种多样性产生的遗传基础,已分离出三类在其5'端附近不同的人LCA cDNA克隆。根据对基因组DNA克隆的分析确定,这些差异是由于三个外显子的不同使用造成的。此外,用LCA外显子特异性探针进行的Northern印迹分析表明,至少存在另外两种由差异剪接产生的LCA mRNA形式。人和小鼠LCA蛋白序列的比较仅在细胞外结构域显示出明显差异。