Mizuno K, Okano I, Ohashi K, Nunoue K, Kuma K, Miyata T, Nakamura T
Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan.
Oncogene. 1994 Jun;9(6):1605-12.
By low-stringency screening of a human hepatoma HepG2 cell cDNA library, using the genomic fragment of chick c-sea receptor tyrosine kinase as a probe, we isolated overlapping cDNAs encoding a novel protein kinase, which we termed LIM-kinase (LIMK).* The predicted open reading frame encodes a 647-amino-acid polypeptide containing a putative protein kinase structure in the C-terminal half. In addition, LIMK has two repeats of cysteine-rich LIM/double zinc finger motif at the most N-terminus. To our knowledge, this is the first protein kinase seen to contain the LIM motif(s) in the molecule. Although the protein kinase domain of LIMK has highly conserved sequence elements of protein kinases, phylogenetic analysis revealed that LIMK cannot be classified into any subfamily of known protein kinases. Northern blot analysis revealed that the single species of LIMK mRNA of 3.3 kb was expressed in various human epithelial and hematopoietic cell lines. In rat tissues, LIMK mRNA was expressed in the brain, at the highest level. LIM is suggested to be involved in protein-protein interactions by binding to another LIM motif. As the LIM domain is frequently present in the homeodomain-containing transcriptional regulators and oncogenic nuclear proteins, LIMK may be involved in developmental or oncogenic processes through interactions with these LIM-containing proteins.
我们以鸡c-sea受体酪氨酸激酶的基因组片段为探针，通过对人肝癌HepG2细胞cDNA文库进行低严谨度筛选，分离出了编码一种新型蛋白激酶的重叠cDNA，我们将其命名为LIM激酶（LIMK）。*预测的开放阅读框编码一个647个氨基酸的多肽，其C端含有一个假定的蛋白激酶结构。此外，LIMK在最N端有两个富含半胱氨酸的LIM/双锌指基序重复序列。据我们所知，这是首次发现分子中含有LIM基序的蛋白激酶。尽管LIMK的蛋白激酶结构域具有蛋白激酶高度保守的序列元件，但系统发育分析表明，LIMK不能被归类到已知蛋白激酶的任何亚家族中。Northern印迹分析显示，3.3 kb的单一LIMK mRNA在多种人上皮和造血细胞系中表达。在大鼠组织中，LIMK mRNA在脑中表达，且表达水平最高。LIM被认为通过与另一个LIM基序结合参与蛋白质-蛋白质相互作用。由于LIM结构域经常存在于含同源结构域的转录调节因子和致癌核蛋白中，LIMK可能通过与这些含LIM的蛋白质相互作用参与发育或致癌过程。
