Yi T L, Bolen J B, Ihle J N
Department of Biochemistry, St. Jude Children's Research Hospital, Memphis, Tennessee 38105.
Mol Cell Biol. 1991 May;11(5):2391-8. doi: 10.1128/mcb.11.5.2391-2398.1991.
cDNAs for the murine lyn protein tyrosine kinase gene were cloned from mouse bone marrow-derived monocytic cells. Comparison of the human and murine genes demonstrated a 94% homology in peptide sequence. Comparable to the human gene, murine lyn was found to be expressed in myeloid and B-lymphoid lineage cells. During the cloning, two types of cDNAs were obtained that differed by the presence (lynA) or absence (lynB) of 63 bp within the amino-terminal coding region of the gene. The genomic structure of the murine lyn gene demonstrates that the two types of lyn transcripts are derived from alternative splicing utilizing an internal splice donor site. Transcripts for both forms were found to be expressed in myeloid cells. lyn-specific antisera detected comparable levels of proteins of 56 and 53 kDa in hematopoietic cells. these 56- and 53-kDa proteins comigrated with proteins produced by in vitro translation or in vivo expression of the lynA and lynB cDNAs, respectively. The two forms had comparable in vitro kinase activities in immunoprecipitates and showed similar peptide patterns, with partial V8 digestion of the in vitro-phosphorylated proteins. The potential significance of the two lyn proteins is discussed.
从小鼠骨髓来源的单核细胞中克隆出了鼠源lyn蛋白酪氨酸激酶基因的cDNA。人和鼠基因的比较显示，其肽序列具有94%的同源性。与人类基因类似，发现鼠源lyn在髓系和B淋巴细胞系细胞中表达。在克隆过程中，获得了两种类型的cDNA，它们在基因氨基末端编码区域存在（lynA）或不存在（lynB）63 bp的差异。鼠源lyn基因的基因组结构表明，这两种类型的lyn转录本源自利用内部剪接供体位点的可变剪接。发现两种形式的转录本都在髓系细胞中表达。lyn特异性抗血清在造血细胞中检测到了水平相当的56 kDa和53 kDa蛋白质。这两种56 kDa和53 kDa蛋白质分别与lynA和lynB cDNA体外翻译或体内表达产生的蛋白质共迁移。这两种形式在免疫沉淀物中具有相当的体外激酶活性，并显示出相似的肽图谱，体外磷酸化蛋白质经部分V8消化后呈现此图谱。文中讨论了这两种lyn蛋白的潜在意义。
