Tamagnone L, Lahtinen I, Mustonen T, Virtaneva K, Francis F, Muscatelli F, Alitalo R, Smith C I, Larsson C, Alitalo K
Department of Genetics, University of Helsinki, Finland.
Oncogene. 1994 Dec;9(12):3683-8.
The Bmx sequence was identified and cloned during our search for novel tyrosine kinase genes expressed in human bone marrow cells. Bmx cDNA comprises a long open reading frame of 675 amino acids, containing one SH3, one SH2 and one tyrosine kinase domain, which are about 70% identical with Btk, Itk and Tec and somewhat less with Txk tyrosine kinase sequences. The amino terminal sequences of these four tyrosine kinases are about 40% identical and each contains a so-called pleckstrin homology domain. The 2.7 kb Bmx mRNA was expressed in endothelial cells and several human tissues by Northern blotting and an 80 kD Bmx polypeptide was detected in human endothelial cells. Immunoprecipitates of COS cells transfected with a Bmx expression vector and NIH3T3 cells expressing a Bmx retrovirus contained a tyrosyl phosphorylated Bmx polypeptide of similar molecular weight. The BMX gene was located in chromosomal band Xp22.2 between the DXS197 and DXS207 loci. Interestingly, chromosome X also contains the closest relative of BMX, the BTK gene, implicated in X-linked agammaglobulinemia. The BMX gene thus encodes a novel nonreceptor tyrosine kinase, which may play a role in the growth and differentiation of hematopoietic cells.
在我们对人骨髓细胞中表达的新型酪氨酸激酶基因的搜索过程中，鉴定并克隆了Bmx序列。Bmx cDNA包含一个由675个氨基酸组成的长开放阅读框，含有一个SH3、一个SH2和一个酪氨酸激酶结构域，它们与Btk、Itk和Tec的同源性约为70%，与Txk酪氨酸激酶序列的同源性略低。这四种酪氨酸激酶的氨基末端序列约40%相同，且每种都含有一个所谓的普列克底物蛋白同源结构域。通过Northern印迹法检测到2.7 kb的Bmx mRNA在内皮细胞和几种人类组织中表达，并且在人内皮细胞中检测到一种80 kD的Bmx多肽。用Bmx表达载体转染的COS细胞和表达Bmx逆转录病毒的NIH3T3细胞的免疫沉淀物中含有分子量相似的酪氨酸磷酸化Bmx多肽。BMX基因位于Xp22.2染色体带，在DXS197和DXS207位点之间。有趣的是，X染色体还包含BMX的最密切相关基因BTK基因，它与X连锁无丙种球蛋白血症有关。因此，BMX基因编码一种新型非受体酪氨酸激酶，它可能在造血细胞的生长和分化中起作用。
