Dual-specificity tyrosine phosphorylation-regulated kinase 1A does not require tyrosine phosphorylation for activity in vitro
Dual-specificity tyrosine phosphorylation-regulated kinase 1A does not require tyrosine phosphorylation for activity in vitro
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DOI：
10.1021/bi700251n
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发表时间：
2007-06-26
期刊：
影响因子：
2.9
通讯作者：
Hwang, Yu-Wen
中科院分区：
文献类型：
--
作者：
Adayev, Tatyana;Chen-Hwang, Mo-Chou;Hwang, Yu-Wen
双特异性酪氨酸磷酸化调节激酶1A（DYRK 1A）基因定位于人类21号染色体，其过表达与唐氏综合征的学习和记忆缺陷有关。DYRK 1A含有DYRK蛋白激酶家族所有成员共有的（YXY 321）-X-319基序。基序中的残基Y321在从大肠杆菌和真核细胞制备的DYRK 1A中被磷酸化。已经提出YXY基序是促分裂原活化蛋白激酶的TXY基序（活化环）的等价物，并且基序处的磷酸化是DYRK活性所需的。在这项研究中，酪氨酸磷酸化的DYRK 1A的活性的作用进行了详细的调查。通过处理E.大肠杆菌产生的DYRK 1A与两种不同的蛋白酪氨酸磷酸酶。所得到的pY耗尽的DYRK 1A在自磷酸化过程中不能重新获得pY，但与未处理的对照一样具有活性。这些发现进一步得到以下观察结果的支持：当YXY基序中的两个酪氨酸残基被组氨酸或谷氨酰胺取代时，DYRK 1A保留了显著的酶活性。总之，我们得出结论，酪氨酸磷酸化和酪氨酸残基的YXY基序不直接参与DYRK 1A的体外酶活性。
The dual-specificity tyrosine phosphorylation-regulated kinase 1A (DYRK1A) gene is localized in human chromosome 21, and its overexpression has been associated with the learning and memory deficits of Down syndrome. DYRK1A contains a (YXY321)-X-319 motif shared by all members of the DYRK protein kinase family. Residue Y321 in the motif is phosphorylated in DYRK1A prepared from Escherichia coli and from eukaryotic cells. It has been proposed that the YXY motif is an equivalent of the TXY motif, the activation loop, of mitogen-activated protein kinase and that phosphorylation at the motif is required for DYRK activity. In this study, the role of tyrosine phosphorylation in the activity of DYRK1A was investigated in detail. Wild-type DYRK1A with a reduced level of phosphotyrosine (pY) was prepared by treating E. coli-produced DYRK1A with two different protein tyrosine phosphatases. The resulting pY-depleted DYRK1A could not regain pY during autophosphorylation but was as active as the untreated control. These findings were further supported by the observation that DYRK1A retained significant enzymatic activity when both tyrosine residues in the YXY motif were replaced with either histidine or glutamine. Together, we conclude that tyrosine phosphorylation and tyrosine residues in the YXY motif are not directly involved in DYRK1A enzymatic activity in vitro.