Sakuma H, Ikeda A, Oka S, Kozutsumi Y, Zanetta J P, Kawasaki T
Department of Biological Chemistry, Faculty of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606, Japan.
J Biol Chem. 1997 Nov 7;272(45):28622-9. doi: 10.1074/jbc.272.45.28622.
We have cloned a novel protein kinase from human cerebellum and named it LZK (leucine zipper-bearing kinase). The LZK cDNA encoded a 966-amino acid polypeptide that contains a kinase catalytic domain and double leucine/isoleucine zippers separated by a short spacer region. The amino acid sequence of the kinase catalytic domain was a hybrid between those in serine/threonine and tyrosine protein kinases, indicating that LZK belongs to the subfamily of the mixed lineage kinase (MLK) family. The kinase catalytic domain of LZK was most similar to DLK (Holtzman, L. B., Merritt, S.E., and Fan, G. (1994) J. Biol. Chem. 269, 30808-30817), MUK (Hirai, S., Izawa, M., Osada, S., Spyrou, G., and Ohno, S. (1996) Oncogene 12, 641-650), and ZPK (Reddy, U. R., and Presure, D. (1994) Biochem. Biophys. Res. Commun. 202, 613-620), which belong to the same subfamily of the MLK family. However, besides the kinase catalytic domain and double leucine/isoleucine zippers, there was no significant homology with known proteins. The recombinant LZK autophosphorylated in the presence of ATP and divalent cations, and exhibited serine/threonine kinase catalytic activity. Northern blot analysis revealed that LZK is expressed most strongly in the pancreas, with a pattern that differs from other MLKs. Expression of LZK in COS7 cells induced phosphorylation of c-Jun and activation of JNK-1, indicating the association of LZK in the c-Jun amino-terminal kinase/stress-activated protein kinase pathway. The expressed LZK was detected primarily in the membrane fraction, suggesting that LZK interacts with other cellular components in vivo.
我们从人小脑中克隆出一种新型蛋白激酶，并将其命名为LZK（含亮氨酸拉链的激酶）。LZK cDNA编码一个966个氨基酸的多肽，该多肽包含一个激酶催化结构域以及由一个短间隔区隔开的双亮氨酸/异亮氨酸拉链。激酶催化结构域的氨基酸序列是丝氨酸/苏氨酸蛋白激酶和酪氨酸蛋白激酶氨基酸序列的杂合形式，这表明LZK属于混合谱系激酶（MLK）家族的亚家族。LZK的激酶催化结构域与DLK（霍尔兹曼，L.B.，梅里特，S.E.，以及范，G.（1994年）《生物化学杂志》269卷，30808 - 30817页）、MUK（平井，S.，井泽，M.，小田，S.，斯皮鲁，G.，以及大野，S.（1996年）《癌基因》12卷，641 - 650页）和ZPK（雷迪，U.R.，以及普雷苏尔，D.（1994年）《生物化学与生物物理研究通讯》202卷，613 - 620页）最为相似，它们都属于MLK家族的同一亚家族。然而，除了激酶催化结构域和双亮氨酸/异亮氨酸拉链外，与已知蛋白质没有明显的同源性。重组LZK在ATP和二价阳离子存在的情况下进行自身磷酸化，并表现出丝氨酸/苏氨酸激酶催化活性。Northern印迹分析表明，LZK在胰腺中表达最强，其表达模式与其他MLK不同。LZK在COS7细胞中的表达诱导了c-Jun的磷酸化和JNK-1 的激活，这表明LZK参与了c-Jun氨基末端激酶/应激激活蛋白激酶途径。所表达的LZK主要在膜组分中检测到，这表明LZK在体内与其他细胞成分相互作用。
